I "crashed" at the 3rd level, came here, and found out the win screen doesn't work. I guess I must've beaten it then.
I do think the game is a bit unforgiving, but I don't think the hitbox is at fault here. The fact that I didn't have any infinity frames after I got hit means I can lose a lot of health very quickly. I also don't know if you're supposed to lose health when you're on top of them.
The core gameplay has promise tho, and the level designs are unique enough to be memorable.