My social role is nothing

I only know a handful of people who I could fairly sum up as having "social roles" in the same way you describe your brother as having. This could be a deficiency on my end, or I could know weird people - or this could be an inadequate model of how social interaction works, and my bet is on the last thing.

they're insecure college freshmen boys

Have you considered making friends with girls? There will probably be less (though still some) of the things you list among girls, depending on what you mean by "inauthenticity". (What do you mean by "inauthenticity"?)

that will probably take at least a couple years.

Have you considered making friends with upperclassmen or socializing with professors you like? Why do your friends have to be your age?

This college is too small for legitimate subcultures to exist.

Just how small is this college? Mine had like 400 people and there were types, if not outright subcultures.

I don't really enjoy anything except playing games

Is there a game store? Those often host gaming events.

and intellectual conversations

Do your friends need to be in-person?

I also tend to be very static and stagnant; one of my major flaws is that I'm reluctant to change habits.

This one could be a problem. Are there any known ways around or through it that are relatively easy to exploit?

I don't really know how to meet new people without broadcasting desperation, either.

Be there to do something else too, and focus (verbally) on that thing (while striking up conversations, of course).