So, the character movement speed seems to change randomly and is very unpredictable, the jump and slide are delayed and because of that the controls feel laggy. I also ended up dying by standing on top of boxes which felt rather punishing since I had so little control over the character to begin with. I would also suggest slowing down the rate at which the parallax background scrolls in as it is deceptive, since the player is very slow but the background looks as if he was traveling in a bullet train.
Also minor thing about the main menu buttons, because they are blurry in a game of pixel art changing their compression no none and filter mode to none, but seeing the rest of the art I think you knew that and maybe ran out of time.
The game looks nice and has nice sound but I think it would be a really good autoscroller with some polish.