The ending was really cool !
I had some little issue with the jump being a bit weird (like low gravity) and hitboxes i had a hard time to understand. The game was also a bit simple due to almost no penalty of death but for a gamejam version it's sometimes better to give the ability to finish the game (especially with the cool ending you made)
Love the rocker idea and the animation (especially the skeleton death animation !)
Music is really a nice feat.
Congrats !