Of course, scientists today do not know everything there is to know. Further discoveries could conceivably show us other things. However, all of the evidence today shows that human beings did originate in Africa.
So far as is known today, human beings evolved in Africa. There have been no hominid remains from before the genus Homo arose discovered in any continent other than Africa. Scientists today are able to use such things as mitochondrial DNA to track human origins. This evidence, as well, indicates that all of the earliest ancestors of human beings evolved in Africa and only migrated out of that continent after they had evolved.
So, while further evidence could someday be found, all current evidence points to Africa as the origin of human beings.