However, human skin is much softer. Because it doesn't suffer the same treatment tanned leather gets. When we're talking about skin, we usually mean something alive, while tanned leather.. well, you get it.
Tanned leather doesn't regenerate and it doesn't have any protective reactions going on (for example, calluses are made by your body to protect the skin so you won't rub your skin off down to the bone). It's just dead, dry, rough, animal leather. On the other hand, if your skin is very dry, exposed to cold or dehydrated, it looks like this: