How do you think they got the mammoth to run into the trap of spears?
Also, in case it turned towards you, you'd want a spear in your hands to make him turn.
Edit: judging by the picture in the post, if you couldn't run away, you might jam the back end into the ground beside/behind yourself and hold up the point so at least he'd be wounded when he squashed you
Is this the Mandela effect here? Are not all of the cave paintings and cave drawings I've ever seen ones of cave peoples throwing spears at wooly mammoths? Have we been Swiftboated by cave people? Stolen cave valor?