I like the art and the super meat boy - game style.
One thing I think you should be aware of when designing levels is how long you need to wait for the moving walls to go to their end and come back again.
The game encourage you to run run run, and also time it right. The first wall in the first level can give you a bit to long waiting periode where you start to get bored waiting for the wall to get back. -It is not game breaking at all but might be a good thing to think of.
It is a nice feature you made that you dont need to respawn at the start of the level when you have made good progress.
The death counter feels like a highscore-thing... I am split between should I finish the level or just get the death count as high as possible... Death in this game feels very rewarding, the animations and feel is good :-)
*Note: The information says you made it with PixiJS, but when the game loads Gdevelop logo appears