So this is basically that one part from Celeste, but instead it's the entire game? Hey, that actually might be a cool idea! Yeah, I'm all for it. Unfortunately, this game has some issues I've noticed. The controls feel stiff, an issue that definitely needs to be fixed. The game also requires precise jumping, and the shadow follows very closely. I feel like it would be better if it was just one or the other, rather than both. Combined with the stiff controls, it makes it hard to pass even the tutorial. And when you die; you see a drawn-out game over screen, and then the menu screen, and then it's back to the start of the level. You should make the game over screen shorter, and add check points.
A great idea, but definitely in need of some polishing. Still, nice work!