If a mod is adding both map gen AND pawns, it goes in Races if it adds items but it's a faction mod, it goes in items etc. Unless stated otherwise, categories further down override categories further up. And make a bunch of empty folders named the various categories in a flashy and attention grabbing manner. This makes sure everything downloaded properly and tends to solve a lot of issues pretty much instantly. If you have not done so recently, I highly recommend that if you use Steam to run Rimworld, that you go into your library, right click Rimworld, Properties, Local Files, Verify File Integrity or whatever it's called. Credit to Felinoel, Chevalier XLIV, and everyone else from Rim of Magic, Madness, LotR, and a few other servers who helped me figure out and post this entire mess of a guide, and the intricacies of modding with Rimworld in general, over the course of like Ya'll are awesome.
References to 'I' or 'me' are because I, Trisscarthe author of this modlist, finally got off my ass and went in to add explanations and flesh out the guide, as before it was short and terse due to Discord's character limit.