You are right, this game is pretty hard. I especially enjoyed how the ghost form works, how Player must use collisions to elevate themselves and how to use gliding smartly. The human form needs more work, it feel sluggish and sometimes can't jump over some platforms. Collision thing mostly but sometimes I died by this and that didn't feel good.
You did a really good job with music, it doesn't feel repetitive and is quite entertaining. Sounds on the other hand needs to be louder. I set slider to the same value and music is still louder than sfx. You should look more into how sounds works (it looks like a logarithm).