Things can’t stay in space without being pulled down by gravity, including all objects in and around Earth. The reason some things don’t fall down is because they are moving horizontally fast enough (and high enough not to have significant wind resistance to slow it down) that as they fall down the Earth curves out from under it and the object misses the planet and it keeps going around and around. That’s what an orbit is.

The image above known as “Newton’s Cannon” explains how an orbit works. As you can see, all objects fall but under certain conditions they fall around the Earth. This requires those objects to roughly travel horizontally relative to the ground as the ground curves around the planet.

Here’s an image that shows how much man-made stuff was orbiting Earth as of 2015. That was before SpaceX started putting over 40,000 satellites in orbit for global Internet access.