It turns out that a single strand of human hair measures 17 to 181 millionths of a meter wide. But anyone who creates or reinvents a fictional species of humanoid has the freedom to change the dimension of the head, including the size of a strand of hair (if they choose to still have hair.)
So in an alternate world, we share that world with another species of Homo, one that still has hair on its head, only that each strand now measures 1/2-1 inch in diameter. The question isn't what the hair would look like--I'm imagining a bunch of leaflike lobes--but what kinds of adaptive advantages such hairs can have for the wearers?
Oh, and by the way, the hair in the question is focused on the head, nowhere else.