Really clever to have as playtesters mice. Maybe it could be better to place the tiles right from the inventory, just to save time for the player. Also it tooked me some time to understand that some mice don't jump and some do. Maybe it could be solved by having third level one jumping and one nonjumping mouse. But other mechanics were nicely broad out from level to level.
Sometimes the mouse got stuct at the side of the wall. It was because there was friction between the mouse and the wall, so by putting PhysicsMaterial2D with friction to 0 either mouse or wall would solve the problem.
But overall good game.