So two things in response to this. First, this article is a horrible one to use since it doesn't include the actual studies it's referencing, but it gives an idea of the range of force for a boxers punch (they also don't specify, but I'm pretty sure they're referring to a cross rather than a jab). The main point of sharing it is that even flyweights can do damage with their punches.
The true force of a boxer's punch
Second, there's a lot more to it than just the strength of your jab. You're not going to knock anyone out with it. I'm going to use I and you in the next part, but don't imagine me vs. you, imagine the stocky version of you that you pictured vs. a professional middleweight.
If we're in the same weight class and I'm like 40 pounds lighter than you, that means a combo of you're slower than me, and I've probably got a big reach advantage. So not only am I hitting you with my jab, you wouldn't be able to do what that short middle schooler did to you. Each time you try to get closer, I'm waiting until you get into my range, throwing 1-3 jabs, maybe a jab-cross depending on reach/speed difference, and getting out of your range/circling out. As the fight goes on, you'll get more tired since it takes more energy for you to continue trying to enter, making it easier for me to do. There is some risk that I'll mess up a couple of times with my timing and you'll get in, but as a professional boxer, I'd be able to handle that a few times as well, and escape again.
And this isn't me 'not being noble', it's part of technique and just how the sport works. It's the difference between an in-fighter and an out-boxer. And it's also how people like Floyd Mayweather do so well.
