Why is this the answer?

The answer is leg because this amazing riddle is a very clever way to trick your brain! It asks about things that a whole person does, but the answer is just one incredibly important part of you: your leg. Let's look at the first clue: "I do not breathe, but I run and jump." Your leg is a body part, not a whole living thing, so it does not have lungs to breathe air. But what do you use your legs for? You use them to run very fast and jump very high! Even though the leg itself is not breathing, it is the powerful part that makes running and jumping happen. Next, the riddle says: "I do not eat, but I swim and stretch." Just like the first clue, your leg does not have a mouth to eat food. However, when you go swimming in the pool, your legs kick and move you through the water. You also use your legs to do big stretches before or after gym class. They are essential tools for all those movements! The puzzle continues with: "I do not drink, but I sleep and stand." Your leg is not thirsty and does not need a drink of water. But when you are standing up, your strong legs hold you steady and tall. And when you are tucked into bed at night, your legs are resting or "sleeping" right along with the rest of your body. They are resting so they can be strong again in the morning. Finally, the riddle says: "I do not think, but I grow and play. I do not see, but you see me everyday." A leg does not have a brain, so it can't think of ideas or solve puzzles. But as you get older, your legs get longer, so they certainly grow! You use them for all your favorite playground games, which is how they play. And even though a leg does not have eyes, you see your own legs every single day when you get dressed or walk around. This riddle is a smart game of words that perfectly describes your amazing and helpful leg!