You got the proof of concept down for the art style and design, but my main feedback which other people also commented on is the level design is what's causing issues with this style of game. The way the level is laid out conflicts with the idea that you need to go fast, so there's no flow. You have a lot of spikes and walls placed in such a way you get punished for going fast, so the player has to go slower, but then the breakable boxes needs the player to be fast, and once they go fast enough to break the walls, they hit spikes.
I see the idea with what you did and would love to play a more fleshed out design. Level design will probably be the hardest thing to do, but once you get a flow going with the gameplay, it would be pretty fun.