It seems to me that you are stating in other words the very idea I try to convey:
The “Lebombo bone” evidences sapiens creatures that may be much smarter than chimps today. By contrast it does not evidence humankind made by God in the image of God, i.e. called and ordered to share eternal life in God (“divine beatitude”).
In my opinion, the historical fact that God transformed Homo sapiens into humankind in the image of God is clearly evidenced by signs revealing awareness of moral and legal accountability, as such signs point to creatures that can fulfill or transgress a law, and therefore freely accept or reject God’s will.
For the time being, such signs have been found only in the Neolithic, later than 12,000 BP.