maybe the first sling was made by some nerdy teenage caveman who had no friends and wasn't allowed to hunt. i can picture it in my head "what is he doing over there in the corner?" "is that string and some rocks?" "he's so weird"

My original post said the first evidence of slings in the Bible was with the Benjamites. However, as found with badgers new post in general discussion. Slingstones are mentioned in Job, which was written significantly before the book of judges. Judging by geneologies, about 400-600 years before.

So slings have been around for awhile.