This is what I learned about this problem so far (from a person nicknamed
3226 in Voat.co):
People aren't living in a forest foraging for food. (Of course not.) We're part of a human society, where we doesn't have to do anything that would wear down or break our nails (in case we want them very long, if we deliberately try to grow them in this way).
Apes' nails would grow that long, but they keep them short. They bite them. For all we're told that it's a bad habit (and it really is!), it's actually the way we've always been taking care of our nails until extremely recently.