This has been bothering me for months now and google isn’t giving me answers. So, how?
ELI5: Our eyes are just good at focusing!
If you’ve used a magnifying glass in the sun you can see how you can focus the light onto a single point on the ground, right? Basically, there is a small magnifying glass behind your pupil (called the crystalline lens) with a muscle attached to it so it can curve and straighten however much needed to focus the light. When you focus on something close up it curves more, and when you focus on something far away it straightens out as much as it can!
There is a sweet spot at the back of your eye (called the maculus) that’s almost right next to the nerve that connects to your brain. Ideally, the magnifying glass gets focused on this part of the eye, sending a clear picture to the brain!
It’s worth noting that some people with really bad prescriptions really do just see a mess of colors without their glasses lol, they really help!
The fundamental way eyes or cameras work is that light passes through a narrow opening, such that light coming in at different angles will land on different spots on the retina, creating an inverted image. You can do a simple experiment yourself to see this, look up “pinhole camera”. Lenses help achieve that with a less narrow opening without blurring the image, and let you focus on different distances, but aren’t strictly necessary.
The pupil of our eye limits the direction the light can hit our retina. We can only see light at a very narrow angle… or else yes, it would be a mess. Old school inuit used to make sunglasses out of leather with narrow slits that would block out light in all directions except for a narrow slice for just this reason, as the snow would cast light at their eyes from all directions and blind them (“snow blind”). This would work today in watery or snowy conditions, and is also why polarized sunglasses work so well in these environs.