In an ideal world, I'd post them properly, but I think it's better for them to be at least referenced here than for me to never get around to doing the former.

- Loy's Goodies - CC0, made using Blockbench (low-poly modeling software usually used for Minecraft); I've been putting it off for months because the conversion process isn't trivial, especially when it comes to rigging

- Everything Library - CC-BY or MIT, assorted made for the video game Everything; ...I'm not actually sure why I haven't posted these! I vaguely recall the website politely asking not to, but I can't find that anymore

- 100 Avatars - CC0, there's actually 300 of them!; my excuse is uhhhh 300 is a lot!

- Microsoft Rocketbox Avatar Library - MIT, optimized realistic human models; MIT isn't a license option here

- wlily - CC0, quirky low-poly avatars (requires an account to download)

- CC0 Game Assets - take a guess :P, swords! (there are plenty more freely-licensed assets on itch.io, so I shan't list more)

A few more that might be updated too often to be worth reposting:

- The Base Mesh - CC0, realistic untextured subdivision-friendly models

- fab.com models by plaggy (some of the more recent ones are AI-generated, you might want to turn them off in settings!) and Nichgon - CC0