Q: If 2D objects have 1D shadows and 3D objects have 2D shadows, are we the shadows of a 4D world?
A: hold on just 1 minute, 2D objects usually have 2D shadows if they are in 3D space, if the receiving surface is 2D. could even be a 3D shadow if the receiving surface is 3D. And this would be all the same for 3D objects also. your story is full of holes actually