When Roger Throws rocks at Henry why doesn't he aim to hit?

Answer 1

The act of throwing rocks at a human being shows the readers that Roger is a psychopath. He deliberately misses because there are still hints of civilization left inside him from his years in Britain.

Answer 2

The only reason Roger doesn't hit Henry is because although he's on an island with no adults, he's used to getting punished for hurting other people. He knows that whenever he does something mean to someone, he gets punished. He doesn't grasp the fact that no one is there to do the punishing.

Answer 3

Because back in his old life, he would have been punished for hitting a child with rocks. He's still afraid of that punishment now, even though he doesn't care if he hurts Henry.