This is technically true only because South Africa wasn't populated by people until white Europeans colonized it.
Had there been africans there, they still would not have been able to build anything, houses, fire, etc, but they didn't because they never lived there until the dutch made it hospitable. The first africans that arrived were the bantu, fleeing the zulu, like 130 years after the dutch.
The only blacks living in South Africa for the first 130 years of its existence were a handful of slaves that the dutch brought with them.