I have two suggestions that could help smooth out the game:
1. an instant restart button so you dont have to jump down to the floor and confirm restarting every time you screw something up (its a minor detail but would really help streamline the game)
2. a bigger hitbox for pickups, right now it usually takes a second or two to position yourself precisely which slows down the pace of the game
you could also make levels revolving around enemies following you off edges to their doom while you jump back to safety.
Nice game btw.