Why are human arms so short if long arms are beneficial for melee and throwing things which were important skills before the invention of guns?
Because you need weight to have leverage. Too large an arm and you try to lift something, you just throw your body. See gorillas. Notice how gorillas arms are huge and their legs are tiny? That's because they walk with their arms. It's called brachiating. Notice our legs are huge? And our arms are tiny? That's because we walk on the ground. The huge limb creates better leverage.
