Can anyone recommend me Public Domain worlds with intense, rich wildlife?

So very brief summary: I'm also part of Reddit Speculative Evolution and I'm close to finishing a pronect involving Greek Mythology and its unique biodiverse world by making a more grounded and realistic scenario for centaurs and cerberuses to exist, and it makes total sense on them being the mythical way they're described while also being plausible to exist within the evolutionary laws of our own world. After I'm done with this world I did have a few projects for the Norse world (with the Vaettir types species) and for Plato's World of Forms, but in all honesty neither of these give me as much of a rich tapestry to draw from as greek mythology would (at least how it's going for me), so I wanted some suggestions. I know the obvious choices of Alice and Oz and fairytales alike, but those either give some more Narni-ish or Tolkien vibes, which isn't a whole lot to work with to be honest. I did thought of John Carter or Cthulhu but these two specific authors are people I try not to get too deep into what they wrote due to their worldviews, so anyway... It's okay of no one can think of anything, totally fine, but if you can, could you suggest me fictional Public Domain worlds rich biodiverse flora and fauna that someone could work woth to create a fictional creatures guide? And thank you for your time! Have a great day!