I always love to see this kind of mechanics of using your past deaths to progress, I think the implementation of this mechanic is really good but the game needs more work as a whole, the mechanic is really good but it needs to be followed by a good map design, some different platforming sections where you can use your bodies.
The death respawn cycle could be done a bit better, specially the part with the cooldowns a way to fix this would be to just recharge the jump and attack after death also with the tutorial guy text box needs a different button to proceed like "E" or "F" or check where the player is and if its too far away the window just closes otherwise you waste your abilities skiping the dialogue.
lastly there are 2 areas in the game where you can fall of the screen this is an easy fix adding some colliders and tiles to hide it maybe even wall it off.
The game needs some work thats for sure but the base its there and it's really good, this mechanic is not used that much in games which is a shame but you can do really cool stuff with it, keep it up.