The First World / Eberron creation myth and the idea that some dragon gods are just elder dragons who are god-like has made me want to build a campaign world where all the "gods" are just super-powerful dragons. I haven't developed the idea very far, but it would make use of the First World / Eberron creation myth for starters.
So there were three dragons who created everything. One killed one of the others, shattering it into pieces, and then the third imprisoned the first and so on. Somehow other, non-draconic creatures have come into being to populate this world that the three progenitor dragons created, but all the "gods" those creatures believe in are actually real elder dragons (or are inspired by them at least). I'm not sure if I'd want that to be a campaign secret or something that is obvious to everyone. Either way could be fun. I could see a world like Theros where the gods appear in the sky and sometimes even walk the earth, except that instead of appearing humanoid, they're dragons. Or it could be more like Eberron, where no one really knows if the gods exist, but the deities that make up the Sovereign Host (or whatever) are actually based on real, god-like dragons.
It requires a lot more thought, and I'm not sure I have the time or mental energy to think it all through yet. (I've been considering asking for help in fleshing it out here but I'd like to get my thoughts gathered together a bit more first.)