Your point is well taken, and that is the mystery of a higher dimension interacting with a lower dimension. Good thinking, to which I add, the 3D character has height and converts the 2D world to 3D with his entering it, but only for his purposes. 3D can “reach” into 2D to alter it, thus the great mystery for the 2D inhabitant, as is it mystery for 3D when 4D interacts with it causing “magic” to occur with the temporary addition of the next dimension for special purposes.