Great choice for colors and assets :) I would recommend to change hitboxes to better fit character’s sprite, and make sure enemies cannot hide behind the player’s sprite. Adding an invulnerability time after receiving damage would be great as well, because you can die near-instantly! It’s too bad because it prevents people from actually playing the game :p The boss came up too early in the gameloop so I never used the shop.
That + sounds would make it a really really cool game!