i've been putting a lot of work into my personal blender asset library lately, and since all of it is CC-0 stuff, i figured i'd clean it up and make it publicly available in case anyone else wants it. right now it's primarily stuff other people's stuff from Poly Haven and Blend Swap, with a few of my own things in there. i'll be updating this as i use it for my own things. even though it's all public domain, almost everything is attributed with a creator and url for the original source.
you can get it here: https://github.com/trashbyte/blender-assets
i recommend cloning the repo with git so you can easily update it. i also recommend you append assets from this library instead of linking them, since it's still pretty new and the organization of things is likely to change and break links.
there's also an asset listing here: https://github.com/trashbyte/blender-assets/wiki
(although i don't know if i'm going to keep this updated the whole time)
"but why not just get polyhaven's own blender addon?"
if you've got the $30 to spend, go for it. it includes everything on polyhaven and has extra bonus features that make it even more useful. this library is just my own thing that i'm making available because why not. also it has my stuff and things from blendswap too.
"this seems like a really random assortment of things"
that's probably because it's a really random assortment of things.