National Geographic has reported an interesting, somewhat controversial, news story on the Hominid species Homo gautengensis. The problem is, that this taxon is not universally recognized by paleoanthropologists as being the oldest member of our genus, Homo. That honor goes to Homo habilis, or "handy man".
Taxonomic 'lumpers' would include this with H. habilis. 'Splitters' would put it into its own species.
The problem is the disproportionate arm length.
Cannibalism cannot be proven, only inferred. Cutmarks on the skull could be from ritual defleshing for burial.