That was really really good! I thought the puzzles represented a good progression from easy to hard. Assuming I completed it correctly, the final puzzle had a really cool finish with having to run beneath the falling block to get to the key.
Regarding that final puzzle, I think it's a little unclear that the switchdoor thing will block the larger block. My intuition was that they would pass through each other. Maybe a puzzle that involves the player walking atop a switchdoor thing would be a good inclusion to demonstrate that its possible?