Really nice work, though I have a big gripe about the character controls. For some reason you're completely cancelling out his velocity whenever he touches the ground or hits a block with his head and it really puts a hamper on the enjoyment. Should just set friction on your character collider and let it come to a stop naturally, or lerp() down, to give it more of a Mario feel.
Also, I've found myself getting stuck in colliders, especially if you have 4+ blocks stacked and you go up close and start jumping, you can nudge yourself in until you die, very odd haha
Cheers.