Objects in motion tend to stay in motion. Sir Isaac Newton devised the first theory of relativity. To illustrate this old style relativity, let's say we have a watermelon and a pane of glass. Where the watermelon and pane of glass end up depends only their relative speed and direction. Once you move the watermelon and glass pane from outer space to our everyday gravity-bound existence, the preceding example is no longer true.
Gravity is an extra force that complicates the equations.
But what really changes everything is friction, that stickiness when two things rub. Friction is the reason why the part Newton's First Law, having to do with moving objects, is so contrary to common sense. The Earth is, obviously, much larger than the watermelon and the glass pane. Objects are constantly rubbing against the Earth and the layer of air it pulls along. The collisions between ball, air and Earth scatter the ball's motion until its direction and speed match that of the surrounding planet.