Thanks for the feedback! Happy you enjoyed it :)
Indeed, you can finish all the levels by becoming undead and clear the levels this way, but only if you finish the six levels without becoming undead, you'll unlock the seventh and last level. And yes, I was considering putting a mechanic that would have you move with the ship, but decided to leave it out to put more focus on having to slow down the ship to navigate more precisely. But indeed, the collision with the cannon was actually the last thing I removed recently, but unfortunately it didn't make it into the final game.
Thanks for the feedback!