5:20 The Lord was sad, when He saw that He had hurt the vegetation, and the non-human animals,
because animals are not bad, they are only animals, and do not KNOW any better, than just to
follow their natural, animal instincts.
5:21 Therefore, God decided, that He would not do that again. The “Rainbow” is God’s guarantee,
that He will never do that again.
But on the last day, how will the animals be saved? Help me understand.
Thank-you for the question.
Don’t know exactly how, but they’re obviously not on trial like we human beings are, and this planet is their home, so it must stand to reason that they will not suffer the same fate as the unreformed human beings will, and as God created and controls all He can make that happen:
The Way home or face The Fire 8:53 You did not come here to destroy and pollute nature, and exterminate the animals; you came here to learn to be good. Man is trying to destroy nature, and the day that he succeeds, you are all dead, and you all think you are sane. This planet belongs to God and the animals, NOT to you, and the animals have more right to be here, than you do. It is THEIR home, NOT yours, and they have the RIGHT to survive.
One passage from the Book which seems to talk about this reads as follows:
Isaiah
34:11 But the cormorant and the bittern shall possess it; the owl also and the raven shall dwell in it: and He shall stretch out upon it the line of confusion, and the stones of emptiness.
34:12 They shall call the nobles thereof to the kingdom, but none [shall be] there, and all her princes shall be nothing.
34:13 And thorns shall come up in her palaces, nettles and brambles in the fortresses thereof: and it shall be an habitation of dragons, [and] a court for owls.
34:14 The wild beasts of the desert shall also meet with the wild beasts of the island, and the satyr shall cry to his fellow; the screech owl also shall rest there, and find for herself a place of rest.
34:15 There shall the great owl make her nest, and lay, and hatch, and gather under her shadow: there shall the vultures also be gathered, every one with her mate.
34:16 Seek ye out of the Book of the “I AM”, and read: no one of these shall fail, none shall want her mate: for my mouth it hath commanded, and His Spirit it hath gathered them.
34:17 And He hath cast the lot for them, and His hand hath divided it unto them by line: they shall possess it for ever, from generation to generation shall they dwell therein.
There are probably many other passages from Scripture that will talk about it, besides this one. But this passage is one that was recently read.
And from this it definitely looks like the animals will not be harmed - quite the opposite in fact.
Ezekiel 39:3 And I will smite thy bow (shooting weapon) out of thy left hand, and will cause thine arrows (ammunition) to fall out of thy right hand.
39:4 Thou shalt fall upon the mountains of Israel, thou, and all thy bands, and the people that [is] with thee: I will give thee unto the ravenous birds of every sort, and [to] the beasts of the field to be devoured.
39:5 Thou shalt fall upon the open field: for I have spoken [it], saith the Lord “I AM”.
Agreed @phithx @LiveWithNature
God has already guaranteed that He would not destroy non-human animals again after the great flood in which only Noah and his family survived.
https://thewayhomeorfacethefire.net/
TWHOFTF 5:20 The Lord was sad, when He saw that He had hurt the vegetation, and the non-human animals, because animals are not bad, they are only animals, and do not KNOW any better , than just to follow their natural, animal instincts.
5:21 Therefore, God decided, that He would not do that again. The "Rainbow" is God's guarantee, that He will never do that again.
It is not currently known how the animals will be saved. That is a secret at the moment.
Scriptures found in The King of kings' Bible - Contents
Deuteronomy
29:29 The secret [things belong] unto the "I AM" our God: but those [things which are] revealed [belong] unto us and to our children for ever, that [we] may do all the words of this Law.
Wisdom
3:21. Seek not out things that are too hard for thee, neither search the things that are above thy strength.
3:22. But what is commanded thee, think thereupon with reverence, for it is not needful for thee to see with thine eyes the things that are in secret.
Inspiration from nature
Earlier today, while out running an errand, some nearby birds were noticed along the way that I was going. They were quite pleasant to watch, and so I started to watch them and their activities more attentively.
It then occurred to me:
Birds are monotheists
They just worship only God throughout their entire existence and associate nothing with Him; and they appear to be constantly giving Him praise, as they go about their activities! It was noticed how that they also seem to be able to enjoy everything that they do. It then occurred that this is the reason why they are this way.
Birds are therefore made free to be able to joyfully live out their existence according to His Will and continually give Him praise. Birds don't have politics and they don't have organized religions (or any of the ideas that collective humanity still has, due to the influence that organized religions have had and/or are still having).
They just are, and they live in complete harmony with God's Will ("islam") whatever that may be for them.
It then occurred to me, that because of this, birds are completely free and they don't have a care in the world.
Then, I could feel my soul begin to sing from the experience. It also felt worthwhile to share something of this experience here. 
It also says in scripture they (and all of Creation) are obedient to God (i.e. they are monotheists) and they don't disobey Him.
It seems that often the simplest lessons (like lessons found in nature) can turn out to be the most profound.
Birds are monotheists! Therefore they seem to be a good example for any of those among humankind, who want to know. 
Kofk Bible
John 8:23 And ye shall know the Truth, and the Truth shall make you free.
Sura 3:64. Say: "O People of The Book (Bible)! come to common terms as between us and you: that we worship none but God; that we associate no partners with Him; that we erect not, from among ourselves, lords and patrons other than God." If then they turn back, say ye: "Bear witness that we (at least) are "True in Faith" (bowing to God's Will)."
Sura 6:38. There is not an animal (that lives) on the Earth, nor a being that flies on its wings, but (forms part of) communities like you. Nothing have We omitted from The Book, and they (all) shall be gathered to their Lord in the End.
Sura 12:38. And I follow the ways of my fathers,- Abraham, Isaac, and Jacob and never could we attribute any partners whatever to God: that (comes) from the grace of God to us and to mankind: yet most men are not grateful.
The Way home or face The Fire
8:55...LEARN from the animals and nature, like the Indians did, and become environmentalists.10:12 The Lord told Mohammed exactly the same as Jesus had taught, which is NOT to worship Jesus, or Mohammed, or any other Prophet or Angel, and to worship ONLY God (Sura 3:79)(Mark 10:18 & Matt. 5:48), and NOT to be priests (Sura 57:27 & Sura 4:152)(Matt. 5:19 & 23:8).
11:57...Jesus himself said that people MUST NOT worship him, but JUST worship ONLY GOD (Matt. 19:16-17 & Mark 10:17-18).
According to the Quran, idolatry (associating anything with God) is the only sin that God does not forgive, while He forgives anything else, to whomever He Wills:
Kofk Bible, Sura 4:48. God forgiveth not that partners should be set up with Him; but He forgiveth anything else, to whom He pleaseth; to set up partners with God is to devise a sin most heinous indeed.
(4:48. God does not forgive association with Him, but He forgives anything less than that to whomever He wills. Whoever associates anything with God has devised a monstrous sin.)
Could what is happening in the world right now be seen as being a result of this? It seems likely. It seems that when it comes to human beings, some of the lessons (or perhaps even the most important one?) have to be learned the hard way. The world is experiencing chaos, but the birds? They seem blissfully unaware of it, they seem to be blessed with happiness and joy.
It seems from this, that human beings might start to do better if they/we were perhaps to aim to see if they/we can now finally begin to learn some more of the lessons that are built into nature.
The Way home or face The Fire
Words of Wisdom 2
Serenity is not freedom from the storm, but peace, brought about by total faith in God and His protection, amidst the storms of nature and of life.
Thank you
“The flowers appear on the earth; the time of the singing of
birds is come, and the voice of the turtle
is heard in our land.” – Song of Solomon 2:12
https://www.twolisteners.org/?page_id=4510
16:79. Do they not look at the birds, held poised in the midst of (the air and) the sky? Nothing holds them up but (the power of) “I AM” (Matt. 10:29). Verily in this are signs for those who believe.
https://jahtruth.net/kofk-free/sura016.htm
24:41. Seest thou not that it is “I AM” Whose praises all Beings in the heavens and on Earth do celebrate, and the birds (of the air) with wings outspread? Each one knows its own (mode of) prayer and praise. And “I AM” knows well all that they do.
24:42. Yea, to “I AM” belongs the Dominion of the heavens and the Earth; and to “I AM” is the final goal (of all).
Thank-you.
Jonathan Livingston Seagull, a seagull who is bored with the daily squabbles over food. Seized by a passion for flight, he pushes himself, learning everything he can about flying until finally his unwillingness to conform results in his expulsion from his flock. An outcast, he continues to learn, becoming increasingly pleased with his abilities as he leads a peaceful and happy life.
Dear @be1 and @NancyDrewberry,
Hope this finds you both well.
You’re both welcome and thank-you both as well.
Wow, what a wonderful day today turned out to be! 
Praise be to God.
Those verses are amazing! @be1 .
And also loved JLS, but haven’t read that in years @NancyDrewberry
Listening to it sounds like a really nice idea and could be done while going out for a walk. 
That gave me an idea, so plan on doing just that (listening to it later) after I have downloaded it.
Thank you both &
God Bless.
It has been said that God spoke to Nikola Tesla through a bird.
Interview: Nikola Tesla and John Smith (From the American magazine "Immortality")
https://www.gongoff.com/joomla/index.php?option=com_content&id=1073:who-is-god-nikola-tesla-explains
Dear @ LiveWithNature
Thank-you for sharing this lovely piece. The birds are in celebration all the time as we should be.
Thank-you @GibMessenger all for sharing lovely things in this regard especially free energy Free Energy, Radiation, War and Water
Sura 27:16. And Solomon was David's heir. He said: "O ye people! We have been taught the speech of birds, and on us has been bestowed (a little) of all things: this is indeed Grace manifest (from "I AM")."
You're welcome.