Why is this the answer?

The answer is needle because this clever riddle uses a super fun word trick to make us think about a tiny, helpful tool! When we first read the riddle, "What has a single eye but cannot see?" our brain quickly thinks of an eye like the ones we have, which help us look at the world. But the word "eye" can mean more than one thing, and that is the secret to solving this puzzle. A needle is a thin, sharp piece of metal that grown-ups and sometimes older kids use when they want to sew or mend things. Needles help to push a long piece of thread through fabric to put two pieces of cloth together, or to fix a rip in a shirt. If you carefully pick up a sewing needle and look closely at the end that is not pointy, you will see a small, oval or round hole. That little hole is exactly what we call the "eye" of the needle. It is where you must put the thread so that it can follow the needle through the cloth as you sew. The riddle is playing a wonderful game with language. Even though the needle has a perfect "eye" shape and name, it is a tool and is not alive like you and me. Since it is just a piece of metal, it cannot actually see the beautiful colors of the thread or the pattern on the fabric. It does not have a brain or any senses to look around. The person holding the needle is the one who sees and guides it. This riddle helps us see how a simple word like "eye" can have two very different meanings. The first meaning is the part of your body you use for sight. The second meaning is the part of a needle that helps you pull thread. The needle is a silent, little traveler that journeys through cloth, creating something new with every stitch, all thanks to its single, unseeing eye. It is a mystery solved by understanding the trick of words! This amazing riddle makes a very ordinary object seem magical.