Here is more from the article in wikipedia:
"Sahelanthropus may represent a
common ancestor of humans and chimpanzees, though no consensus has been reached yet by the scientific community. The original placement of this species as a human ancestor but not a chimpanzee ancestor would complicate the picture of human
phylogeny. In particular, if Toumaï is indeed a direct human ancestor, then its facial features bring into doubt the status of
Australopithecus whose thickened brow ridges were reported to be similar to those of some later fossil hominins (notably
Homo erectus), and where the brow ridge morphology of
Sahelanthropus differs from that observed in all australopithecines, most fossil hominins and extant humans."
So the theory is that maybe Sahelanthropus is a "direct human ancestor," (maybe) and of course that would entail the idea or theory that humans EVOLVED through a further series of formations to become the present human structure.