The first time this situation existed civilization was destroyed by water. This time: fire.
Yes, the creation of human/animal creatures was covered well by Erich Von Daniken in his book “The Return of The Gods, Evidence of Extraterrestrial Visitations.”
Is his book a work of science fiction or is it a recount of ancient history?
This earth has been here for millions of years and has been host to other civilizations before this one. Some, much more advanced than us, may be still here and responsible for the phenomenon that are seen, in the sky, and called UFO.
legends and other sources seem to point to ancient history.
Best to keep an open mind, just out of curiosity.