Any homebrewed setting ought to be an extension of the creator's strong reaction to or against some aspect of the fantasy genre, or of the D&D game in particular - otherwise, why not just use a prepackaged setting, right? As such, there's a need for some higher-level articles addressing 'why is there magic?' 'Where did the gods come from?' 'Where did the Elves, (and Dwarves, Gnomes, Halflings, Tieflings, and Kenku, and etc) come from?' Those sorts of higher-level overviews will be collected in this category. Credit to Matt Colville in his great video here.