I found a site with as many CC0 game assets that you could ever need. These are colorful and mostly 2d platformer and isometric RPG. There are also a few 3d assets mixed in. Please consider supporting the artist, as he’s only asking for a $9 donation and has clearly put a lot of time into creating these great products.
I will be using some of these for a game I’m working on with my nephew, so I’ll share the results when I get there.