Pretty fun mechanics and concepts. A few points though:
- The jump is a bit floaty and it's difficult to land and jump again without the shadow catching up. This could also be helped by increasing the delay between you and the shadow, seeing as the shadow is pretty much right behind you.
- The death animation is way too long and it's frustrating having to go back to the main menu each time you die. For a challenging platformer it should be a quick death animation with the player immediately restarting at the beginning of the level (think Celeste or Super Meat Boy)
Good work overall, the mechanics and the level design look promising.