Very interesting idea! I think spikes are not really the best fit with this concept, as death kind of breaks the flow of the game. Rather, I think it could benefit from leaning much more strongly into the puzzle platformer patterns such as switches and keys.
It could be really cool to manipulate things in the world using th dimension switch, like moving a ball horizontally, then coming up below it and switching to vertical to make it drop down, etc.
Good luck going forward! I would love to see a full-fledged game come out of this!