There simply isn't enough space for your atoms to pass through the atoms of a solid object. You can swim in water and walk through a gas because the particles are so spread apart, but you cant walk through solid objects because the particle configuration is extremely dense.
we can not see atoms because they are so small that the electrons can crcle around the atom many tmes. the protons and neutrons in the neucleus are so small there can be lke 300 klograms of oqygen radon or even hydrogyn n your house and not even know it. that just proves that you cant see atoms