I'm going to make this simple. So say you can see a cube.

You have height, length, and width.
4th dimension has depth.

But here's the catch. This is technically a 4D object.

You see it's height, length, and width. But see the parts that stick out at you? Is it width with height and length? No. As the aren't attached to the original height, length, and width. So it's depth. From front view, it looks like it's pointing deeper out at you. Width can't make this kind thing. So depth is comprehendable. Tell me. If it's impossible for a being of 2D to see in 3D, how can we possible conceive of 4D like physicist claim? so we're actually IN the 4th dimension. As if we were in 3D, we would just see cubes and other basic 3D shapes.
I know it's BOUND to be flawed, so don't mind contradicting it.
(Btw, this is only theoretical.)