They weren't cave men, they had plenty of metal stuff.
These dodecahedra are vastly over-complicated for "utilitarian" uses. As Boinkage says, if you need something for fastening some ropes together just to lash stuff, why use an intricate forging like this? All those knobs, the complex hollow shape, the variously-sized holes, those are features that took a lot of work to add. If it's a utilitarian piece then those features need to be for something. Otherwise we'd be finding examples of simpler versions that lacked those features.
The "they could be for knitting glove fingers" idea, for example, could be just as easily done using a hunk of wood with five nails driven into it.