Fun game, really enjoyed! A few suggestions:
Mouse OP, pls nerf. (Legitimately, though, mouse is just WAY too easy to use.)
The sound for hitting your side is really weird. Wouldn't it make more sense for it to be kind of a clacky sound rather than a whoosh?
It seems like the ends won't bounce if you don't hit the wall with any speed, which is pretty janky. Doesn't happen often though.
Achievements! Something like "beat a level without banging your side" or "collide X times in 5 seconds". I think it would give some nice replay value.
Perhaps different types of terrain, or physics-affected terrain?
Things I would like to see more of:
Shortcuts. Spices up speedrunning and is just fun to attempt!
I like the song choice! Really ensures the player won't get frustrated. I could try to make a song for this game, if you want?
The level design somehow manages to amplify the fun of the main mechanic! Not sure how you pulled that off, haha, but keep it up!