What humans used knots for?
Just look at what early humans would have used knots for:
* Tying clothes together to make them warmer
* Making pouches to carry water and food
* Making bows and arrows to hunt and defend themselves
* Aiding in delivery of the young and fixing wounds
* Tying up bad guys so they can’t escape
* Tethering the family mastodon
* Having something to complain about after marriage was invented