I absolutely love this game. Did you build a level editor or did you build the levels by hand ?
This kind of game where you can backtrack and make better scores to help you for future levels really works when implemented like this. I really think you nailed both the macro (advancing through levels) and micro (advancing in a single level) with a very good link between both.
You perfectly respected the jam theme. The artwork is cute and sober (which I really like). The amount of levels you can build with the mechanics you created is nearly infinite.
Really, GGs. Probably my favorite game so far.
PS : and there are multiple characters with different powers!!! How good is that???