In all seriousness, I guess it sort of depends on what "demographic" your own art tends to appeal to. I seem to get a lot of early twenty-somethings looking at my particular brand of humor, maybe the occasional older teenager, for instance. I actually joined this site myself quite late, in my mid-20's, but I often get the impression from what P-Bot and the Front Page tends to feature that I would have liked this site better as a consumer of content (rather than just as a creator of my own submissions) if I were still a younger teen, horny enough to even watch bad animations simply because it features a cute cartoon girl being cute while not QUITE crossing into "fetish" or "weird" territory. At my current age, though, I find that stuff kind of dumb and gravitate more towards stuff that reminds me of the gross Nickelodeon and MTV cartoons I used to watch as a wee lad.
I guess if I had to pin down a demographic, though, not just an age one, Newgrounds seems overwhelmingly dominated by artists sharing tips with and collaborating with each other--which seems fine, especially when you are first learning, but eventually you have to be able to make your stuff appealing to the average layperson non-artist, which inevitably means you have to post somewhere much more "mainstream" than Newgrounds like YouTube, BlueSky or Instagram to reach a wider audience. I like that Newgrounds seems to be a cozy little place to return to every once in a while to make less "marketable" art for fun or ideally get more nuanced compliments and critiques from fellow artists that most comment sections don't enable--like, imagine trying to get nuanced, essay-length feedback on what you could improve upon under a YouTube video, or anything between the extremes of your followers/echo chamber putting you on a pedestal and haters trying to "cancel" you because they somehow figured out your voter history...