In a random episode of Life Noggin, narrator Pat Graziosi who voices the animated Blocko explained why humans can’t walk through walls despite being made of much of the same material as the wall itself. This, Blocko explains, has to do with the concept of the Pauli exclusion principle, a quantum mechanical theory that essentially states that two identical electrons cannot exist in the same place at once nor can they ever really be touched.
You know how the negative end of a magnet repels other negative magnets? That’s what’s happening when you try to touch anything. It’s like there’s a little invisible force field between you and everything you touch. It’s poked and prodded, but never broken. It’s the same with everything else in the universe too. Now, you obviously can’t, but if you were to actually walk through a wall, it would basically break science.