Natural and even if there was hair on it from ancient man the hair wouldnt still be on it. Have you ever seen anyone post a artifact with hair on it?
I've never seen a post on TNet, but ab 5 min from my house is Russell Cave
https://en.m.wikipedia.org/wiki/Russell_Cave_National_Monument
In there little museum exhibit they have pieces of pottery lined w/ hair.... I think the type of pottery is called crog or grog.