Maybe wearing a wooly mammoth tiara was a great hangover cure.
It may well have been a burial item, some adornment of the body of the deceased. The whole cave could have been a charnel house, for all we know, wouldn't surprise me. There's been a "cave man" model in use pretty much since the discovery of cave art, and Erectus remains were found walled up inside caves, and the first (and many subsequent) Neandertal remains. It's be analogous to saying that the Egyptians lived in their tombs.