Very fun little game! I love the fact how responsive the inputs were, felt really satisfying. The graphics were amazing, too.
The things that I would suggest you to improve/add would be different costumes for the enemies that have to be defeated by different heroes, for more logic. Different backgrounds after some time (maybe like a new landscape every 7 days with a boss at the end of them) and maybe also some medals. Other than that, the game was really neat and enjoyable. Good job on this!
Probably my favorite c3jam entry so far ^_^