Really cool pixel metroidvania! And not only because I love this genre, but because I loved atmoshere and concept of head detaching. Some ideas to consider - MORE parts to find,connect,replace to give you extra powers - temporary or constant! And a bit more sounds would help to feel the level more.
P.S. Seems you have a bug - if you die (lets say when you detach you head, miss the text how to teleport your head and accidentally roll to the deep down :D), then you respawn at first checkpoint and detaching stop working.