Can we stop extending "just a kid" into ever older years? Society already years anybody under 18 like they're the same as a goddamn fetus. Human life expectancy being what it is, we shouldn't be treating people... not even like they don't know anything but like they couldn't even conceivably know anything for fully a third of it.
I don't know how it is for you, but when I look back at 24-year-old me, I am not impressed. I guess what I'm saying is that there are a lot of us who definitely don't have their shit together when they're 24. They say your prefrontal cortex isn't fully developed until 25 at the earliest, but I feel like it was closer to 30 for me. Granted, I'm kind of a dummy anyway, so this probably doesn't apply to everyone.
I don't look at other people as if they are or were me, I look at them as if they are their own people who may or may not be living their life differently from me.