I've heard that standing upright was a major part of what makes humans human with us able to carry things in our free hands. But surely the creation of bags to hold more things and freeing up the hands once more would of been another major step forward. But I've never seen them mentioned in any review of human history. Same goes for belts and things. Or is this question too far back in time for AskHistorians.
You might find more people better suited to answer this question at /r/askanthropology. However, since the earliest bags would have been made of perishable textiles or skins, it might not be a question we can answer with much reliability.