It’s less a trade secret and more a part of a hobby, but if you’re ever bored and in a theological state of mind you can trace a lot of religious or mythological stories to older religious/mythological stories.

For example, the Garden of Eden (Which a lot of people assume the Catholics still stand by even though evolution was accepted a few Popes ago) can easily be recognized as a nod to the Norse goddess Idun who grew golden apples which granted immortality to the other Norse deities. I assume that the Garden of Eden tale was created as an attempt to try and convert the Vikings to hopefully lessen the pillaging of churches.

Another fun one is that Aphrodite is just the Mesopotamian goddess Ishtar after being filtered through another nation and their culture.

Also pretty much every religion I can think of has demonized snakes and serpents with the one exception coming to mind being Quetzalcoatl. But like, Quetzalcoatl was an Aztec deity, and the Aztecs also worshipped a Flayed god who may have been a god of household chores. “Ah yes, his skin was torn from his flesh. He must surely be here as a warning to those who refuse to clean up dust before having guests.”