I think it's a mix between art-style and salvaging minor mistakes

I think part of it is basing everything off adult human proportions. Like top right has a fat old man face in a cat body, and bottom left has like a buff human body with a cat head.

It's similar to old paintings of children and babies, where they've just done an adult human but smaller, instead of looking at how the proportions of small children are actually completely different.

Lead paint.