Gravity_how we stick to the ground though not too much so we can't morning around
It's how we evolved. The mass of Earth defines how strong the gravity is, and as a result, all the life on our planet evolved with that force in consideration. This is why insects don't get to grow larger than a certain size, because their bodies would collapse, and it's why birds have a certain body to wing ratio that allows them the strength to lift their bodies into the air.
Larger bodies have stronger gravitational pull, and if we were there, we'd have a harder time lifting ourselves and moving around. Smaller bodies have less, which is why when you see footage of the astronauts on the moon from the 1960s, they're bounding around like it's nothing at all.