Not true at all. Even if left to their own devices, the Congo is the "Africa of Africa" where the tribes of the Congo consider the pygmies to be subhuman (to this day, pygmies are not considered "human" under Congo law) and regularly massacre them or kill off rival tribes.

If you don't believe me, look no further than the prolific nature of the Bantu culture and language of Western Africa, that's there from butchery and conquest and had nothing to do with colonists. I don't think any of the worst dysfunction that Africa has to offer is ever staying contained.

Circling back, the colonial model that the UK promoted of "civilizing" the third world is probably the best way forward to a functional world.