Well, if major religion, it definitely needs to have lasting power. My guess could be that it starts out as a fertility cult/mother goddess that just absorbs the rest of the deities within it.
I mean, look at how things were before Judaism. Supposedly, Yahweh was just a war god or a personal god of a tribe that just grew in importance as a result of the Israelites’ victories and such. So I figure something could happen.
It all depends on the where though