I really struggled with how to introduce deities into my world, just did not like my ideas. And the players weren't looking to engage with anything that needed deities, like we didnt have any clerics or paladins, and the lack of temples, worshippers, etc., just went mostly unnoticed or unmentioned.
So after a few years, I mean. I just kind of went with there being no gods. When it finally became relevant to talk about it, I didnt want to just say "uhhhh, yeah, war god has been here this whooole time." So I said there used to be gods but not anymore. Some things that are usually of divine domain have been taken over by others. The vagueness at the time was presented as a mystery because time has moved on for so long that there are no mortals who even know what a god is, and most immortals too.
This ended up being latched onto and became a driving force for the rest of the 8 year campaign. I created a divine war that ended eons ago, between the gods who wanted to sacrifice the world for their own survival and the gods who wanted to sacrifice themselves for the world's survival. The latter won, and they followed through. The gods removed themselves. Eventually the party learned of a threat beyond the Beyond, out past the Outside. A threat that made gods afraid enough to choose between destroying their tether or destroying themselves to avoid it.
The BBEG of my campaign became someone who also came to this knowledge, and who wished to call this Entity forth. His motivations for doing so were thwarted, but the summons went through and the Threat became imminent. The party accumulated as much remaining divine energies they could and fought a three-stage battle that I definitely based off of the OG FF7 final boss fight, against an eldritch horror who preyed upon gods.
The party did win. The threat is over. Deities can now exist, and the party is choosing to relinquish their powers rather than rising to godhood themselves. So for the next campaign, when we get to it, I'll be right back to where I started.