Thank you so much for the feedback!!
I honestly thought the tiles from level 1 being permanent was a good idea that would lead to more interesting levels. It forces one to improvise. In hindsight, I can see how withholding that information can be a bad idea though.
This isn't the first comment about the player's friction, which keeps surprising me. My only excuse is that I play a lot of Super Mario Bros. 3, which is notoriously slippery, and I keep forgetting that most platformers have way more friction.
The art for the background started as an homage to SMB1's background, and I wanted to go back and make more decorations (add parallax, trees, other subtle background elements) but I prioritized art for the cutscenes, and didn't have time to circle back to that.
I'm glad you enjoyed the story and cutscenes! With the past few jams, I've been trying to find the best way to add as much story to a jam game as possible, and I think I'm figuring it out. Also, thank you for sharing the level code!