Occurs to Me that African Wars are Ceremonial

 The guys hooting at each other like chimps don't seem to be genuinely trying to kill each other because they're not genuinely trying to kill each other. The guy who shoots the odd arrow does so to make the ceremony less ridiculous. He's carefully aiming at where the other guys aren't, and the bow is so weak that it's unlikely to kill anyone even if he misses the empty space.

 Humans are animals, especially tropical Africans. Animals spend lots of effort to avoid fighting. There's a bunch of posturing to try to work out who would win, and outside desperate cases they agree that one would win and the other backs down. In humans, a pack-hunting species, the posturing is a group effort. Humans can also posture purely to inflict the costs of posturing on the other side. Karen wants to lodge a complaint with management, 50,000 BC version - she's not serious enough to sue, though. 

 If a tropical Africans actually wants to kill you they fire a poisoned missile with a full draw from ambush, they don't snap off a half-cocked clean projectile while leaping around like an idiot in full view. Look, even 80 IQ isn't that dumb.

 The problem is these tropical Africans come to modern society and try to have their ceremonial war using modern non-training childhoods and modern weapons. They hold the gun sideways and don't aim because they don't want to hit anything. Unfortunately, they round 'unlikely to hit' to 'impossible to hit' then fire way too many balls to safely not hit anything. Notice how if someone is injured in these rituals, the ones with the guns are the ones who panic. "Oh shit I didn't mean to hit anyone." The side with casualties are happy because they now have an excuse for lethal "retaliation" - it's not like the dead guy was going to live much longer anyway. Short life strategy. 

 Europeans are killers, anomalously. Probably a recent adaptation to technological advantage. 

 Imagine what a British WWI officer with a brace of pistols could do to these prancing African "warriors." He could probably wipe out the tribe without even taking an injury 90% of the time. "Funny thing, snipers." *bam* "Oh dear, seems the sniper is dead." His only real issue would be killing them all before they ran too far and vanished into the brush.

 If you have armour and the other tribe doesn't, it's not time for posturing anymore. You can gain a lot by going in there and simply butchering them. Strong Darwinian pressure.

 Europeans had to evolve more sophisticated versions of ceremonial/posturing warfare, once someone had the bright idea to make weapons for killing instead of for looking scary. Consequently Europeans normally don't try to posture using live ammo. For the European, once weapons are involved it means posturing and negotiation has broken down already and it's a real fight. 

 Children have residual Africanness and that's likely why they think weapons are toys. A Bantu getting into his dad's bow and arrow is not likely to successfully do anything except whap himself in the face with the stave. Even less dangerous than a kitchen drawer, and there's no locks on those. A Euro getting into his dad's rifle cabinet, on the other hand...