I don't recall Darwin ever postulating "multiple origins". In fact I believe he was the one who first suggested that all currently living members of a species are in fact descended from a single pair in the distant past. All others are dead ends. The idea that all humans currently alive are descended from a pair who lived in Africa two million years ago is not really questionable. What is a false representation IMO is the suggestion that there were never any other species alive at the same time. There were others, probably tens of thousands of villages, each distinct with their own language and culture and lineages, but almost none of their descendents survived to the modern era. Most of these distinct cultures today are represented by a few dozen survivors isolated in jungles and other remote locations.