Ah, the prologue. The bane of writers everywhere. I’ve been struggling with mine as well, having a completely different universe with completely different species. So I understand how you feel. Publishers hate them, readers skip them (or so I’ve heard most people say), but I disagree. I think prologues can add more essence and sets the overall mood for the story.
I agree with the excellent pointers others have made above me. For prologues, it’s best to keep it short but not necessarily clear. Sometimes, it’s mystery that intrigues readers to keep reading on. Don’t be too vague with the prologue too, though, just a lil’ information will do
In my opinion, I think it’s better to avoid the good old “Once upon a time...” and try to make any narration clear-cut, simple, and straightforward. Sometimes, dialogue and narration might not even be needed! Maybe you can take a part of the story (usually it’s the climax, or near climax) and show it in the prologue, just to make readers go, “What just happened?” and flip on to the next chapter where your character is investigating some myths, handing out the first piece of the puzzle for the readers. Let the intrigue push them on.
I don’t know if what I said was helpful haha, but I hope it helped you a bit. Best of luck!