Yes the art-style isn't terribly consistent as I'm not a professional artist while my friends are. The level art clashes a bit with the character art in terms of aesthetic. Personally I feel it also works as providing visual contrast between characters and environment.
I didn't feel consistant polygon or texel size was relevant in a gamejam game so we didn't sweat that too much, nor did we count polygons at any point really. Like some of the tiles are only 28 polygons while some are a bit more when they have some details. I couldn't say about the characters.