WOW it's simple but it's really fun. Love how it looks like just regular platformer until the enemy comes raging at you.
The visuals and the music are really well done. The mechanics work very well and the game is very much fun.
A place to start if you were to consider working on it after the jam is if you die on the boss, and reset in either way, the boss's health isn't reset and sometimes the boss doesn't even come in anymore. Luckily you have a convenient level select that helps a lot with this to work around it by just reloading the page.
Nice job on this game!