By the Gods

Let us consider how in the real world there are various names and faiths in "modern" monotheism alone. Biblical culture can't agree on what to call God or which version of [basically] the same tale is "the truth."
If we wind the clock back to pre-Roman polytheistic cultures from the cold north, to the rainy isles, to the balmy ocean, all had a smattering of gods over varied realms/domains.
Then the Romans adopted Greek gods and changed their names. Then they took them to the 'barbaric' world where they intertwined with Norse and Celtic deities. And then when Christianity was introduced to the heathen pagans, myths were adopted and adapted that further jumbled everything up to and including modern holidays and names of the days of the week.

Now keep in mind, that's just among real world humans whose only concrete, scientific separation is geography. Religious wars are some of the bloodiest, darkest moments in human history. It's not like they're elves and dwarves and goblins arguing theology over a cup o' tea.

So when crafting your own gods and religions for stories and games, where should you begin?
Some might say "at the beginning". Seems logical enough. But that's a big bite to try to take on a whim. How did this all start? When? How long before the present? How is it that the creation myth is known and passed on?

Another issue is that you're trying to compartmentalize...well EVERYTHING! That's, like, a lot. Maybe you don't work in such a linear pattern. If your noggin is anything like mine, it spits out what it wants, when it wants. I can't say "ok brain, gimme a Genesis." I've had more mythos and parts of godly personalities spring to mind at random than I could effectively summarize for blogging purposes. Go with your gut. Relax. Don't try to push it just to make something. That's a sure fire way to get a doosie of an imagination hemorrhoid. Ew.

Maybe these will ease your discomfort and help get the juices flowing in an organized and easily digestible manner:

Sarah Snyder's tips on creating pantheons and religions

Michael James Liljenberg's Genesis How To