While Moses Malone became the first player to jump from high school to professional basketball, it wasn't as easy as simply entering the draft. Back then, the NBA had arcane rules that tried to prevent players from leaving college early, and it took the advent of the ABA to push the NBA to allow hardship cases.
Malone's storied career outshines many other players that jumped straight from the high school ranks. Was it better than Kobe Bryant? Kevin Garnett? Looking at his whole body of work, and in particular who he had to battle against, this answer becomes more clear.