I really liked this game.
It was a bit hard to understand the final jump of the level. The boss is really cool, but too hard for me, one pattern was impossible.
I was in love with the music !
Your game was really like undertale, a bit junky but really really charming !
And your level design is on point !
The player is a bit floaty and you don't have acceleration or deceleration so it feel a bit rigid. Also you have no deformation to increase the feeling of movement (may be something to implement for futurs entries)
Appart from that your game have it all. Good job !