I say supposedly because I know Jonathan Blow paid someone to do all the art for Braid, and licensed all the music (I even saw him demo Braid before release with his programmer art at GDC back in 2008, it did not look anywhere near as pretty, so he made the right choice). But the artwork was so extensive I'm not quite sure that really counts for your criteria.
That may be true for some of the others in the list as well, if that's the case. Stardew Valley I know was all one person, though. Also I really enjoyed Gorogoa, even though it's a smaller game, and that was done by a single guy who quit his cushy tech job and spent 7 years teaching himself how to draw and make games before he released it. It's a super clever interactive comic panel puzzle game that was well-received, though. Think it's on Xbox Game Pass right now.