Why a thrown ball follows a parabola
Two simple motions at once: steady sideways, accelerating downward.
A ball in flight does two things that have nothing to do with each other. Sideways nothing pushes it (leaving air aside), so it keeps its horizontal speed. Vertically gravity pulls it down and changes its vertical speed by about 9.8 m/s every second.
Put the two together and the path is a parabola. The launch angle only decides how the starting speed is shared out between the two directions.
A steep throw buys time in the air but little sideways speed; a flat one the reverse. On level ground the two together carry the ball farthest at 45°.
On level ground the range is v² sin(2θ) / g. At 20 m/s and 45° that is about 41 m.
Start from a height and the best angle drops below 45°: the ball has extra time in the air anyway, so more of the speed is better spent sideways.
Answer it first
On the Moon gravity is about a sixth of Earth's. How does the range of the same throw change?
Show the answer
It is about six times longer: the range is v² sin(2θ) / g, and g is six times smaller.
Reading is not learning it
Leo teaches this at your pace, asks for your attempt before he shows his, and checks a week later what stayed.