I find it strange that atlatl / spear throwers were not commonly used in Africa, they were found in many cultures and time periods. In fact according to archaeological evidence, the atlatl first made its appearance between 25 000 and 40 000 years ago in the region that today encompasses Algeria, Morocco and Tunisia.
It allowed a 6 foot spear (or more accurately a dart) to be propelled at 80 mph with great accuracy ( to around 40m )and reach distances of 200m. The world record for the javelin is under 100m.
An effective, simple weapon, in Africa's long past that lost favour?

It really is a puzzle.
The mental picture of hoards of Zulu using these weapons against the British, suggests that perhaps they would have gained more victories than they actually did.