(trying to sleep. maybe letting some words out will help. no longer the case, having fallen asleep then and finishing now days later.)

Worlds have to come from somewhere. Either you start with something from nothing - divinity or not is detail - or your world is eternal, infinitely old.

Most of my worlds do not have their origins decided. Some do. Others ought to, unless they're for something like a self-contained short without room for that to matter, so long as the setting is. Sometimes the story of the world is the story, like the story of our world is physics and chemistry and contingent biology and history - no over-arching metaphysical dictation or plot, just a bunch of stuff that happens. Of course I may be biased like a fish because this is default. Other worlds, their story is strongly shaped by their origin, their nature - or vice versa - enough to trivialise telling other stories there. Middle Earth, for example, always felt too filled up by its stories to me to have room for others.

I should not complicate this too much with tangents. Mostly I was being struck all over again by the thought that a world's origin and history are probably very important parts of its present. Don't seem to see that often addressed in stories, but usually the characters don't have access to that information either so perhaps it's only to be expected.