The human eye actually sees everything upside down.

Light enters the eye through the cornea and is further refracted when it hits the lens. Here it is flipped upside down and projected onto the retina. The images we see then remain inverted until they reach the part of our brain called the visual cortex, where visual information is processed, enhanced, and reconfigured into the finalized images that we see.

A fun way to test this is to gently poke the bottom right side of your eyeball through your bottom eyelid. You should then see a black dot at the top left side of your vision!

Check out this diagram for more details.