Smoke and mirrors. Improvisation. You define a lot less than you describe, both in terms of entities and details for each entity. And while consistency is an issue, TTRPGs are an ephemeral enough medium that people aren't going to analyze it the way they will a book or film. And there are lots of ways to rationalize apparent inconsistencies; working the rationalization into the background of later adventures so it is revealed as if it were a campaign secret that was foreshadowed by the seeming contradiction is a thin that happens.

The hardest part is often recognizing how much you don't need.