Has anyone ever thought that the reason we jump and fall back in the same place is because the earth is not moving?

That was the way most people thought centuries ago. We now know without a doubt that Earth orbits the sun. The reason we fall back to the same place on Earth after jumping is because we are moving with Earth and continue to do so because momentum is conserved. An object in motion will stay in motion at the same speed and in the same direction unless it is acted upon by an outside force. If you are flying on a passenger jet and jump up, you will land on the same spot on the floor that you jumped from because you are moving at the same speed as the plane.