First, the throw of the ball involves a lot of physics. The wind up to the throw involves the use of many muscles to not only move the arm but to gain momentum to throw the ball with a force. Since muscles are very complicated and the wind up for a throw is not a simple motion, I will present a simpler version of a throw to explain some of the physics behind a throw.
This image shows White Goodman gearing up to throw the dodgeball. For this example, we will say he is only throwing using his forearm (keeping his elbow at 90 degrees). In this example it is a torque problem. There is the force that the arm exerts on the ball to hold onto it (centripetal force) and the torque of the ball. When Goodman lets go of the ball, the total force that he exerts on the ball will be equal to the instantaneous torque of the ball at the moment of release.
When the ball is in the air gravity and air resistance are the two forces acting on the ball.
Lastly, assuming the person doesn't catch the ball, the hit of the ball against the target represents a perfectly elastic collision. In this case both momentum and kinetic energy are conserved, and the force the ball exerts on the person can be calculated.