The pixel art here is quite stellar for a game jam entry - it felt consistent throughout the level and the elements within it, which I feel is quite often not the case with some pixel art games. Excellent job on that.
Others have already mentioned the stranger aspects of the enemies, so I won't get into that; I do think the environment could be used to better effect - I had a strong urge to break every object on each level, and really would have liked to discover anything within them, whether that be powerups or health boosts. Just something or another to reward the player for interacting with the level.