If you're walking while you jump and you hit a wall at all, you slide on the wall and it makes you not be able to complete the jump. It also sometimes gets you stuck on the corner and you have to jump to get off.
Also it would be cool to see some other game mechanics. The maps follow a general pattern and it can start to feel pretty monotonous after awhile. If you don't wanna add new game mechanics, you could try making the levels super unique. Think Portal. They used one main mechanic throughout the game (with the addition of others) but they kept expanding how it could be used, which kept the levels feeling fresh and challenging while having a noticeable skill curve.
I could be wrong about the later maps feeling the same because I didn't play through the entire thing, but from my brief session that's what I got