I suck at making small talk! Most of these kids have something in common, they went to the same undergrad, know the same people, something. When I'm standing beside someone I can't just instantly find something to talk about. Theres too much awkward silence.
Small talk is an acquired skill.
I'm fabulous at it because I was always the new kid in school what with a military dad and a foreign mother, we traveled/moved a lot. But I wasn't always that way; as a matter of fact, I was quite shy as a child and I still hate talking on the phone.
You can teach yourself to become a better socializer and conversationalist; IMHO it's important as the friends you make in medical school may become lifelong ones and it will be professionally important as well. Unless you go into a non patient care specialty, you'll be meeting dozens of new people per day and all of those encounters will require some form of small talk. Patients love a good physician that they can talk to on a human level, not just professionally.
So start by focusing on the commonalities, not the differences (which you seem wont to do). Everyone experiences weather; a trite conversation opener but it's a good start. If you're new to town, you ask those that are from the area about what to expect or comment, "Wow really humid today huh? I though I was going to need a knife to cut through that air!" Everyone loves to be complimented; despite what some men would claim, it's ok to tell another guy you like his shoes or shirt. Or compliment them on their haircut and ask if they had it done locally. Maybe you want to join a gym and ask if they know a good place (this doesn't even have to be true, it's just a conversation starter). Memorize a good joke and tell that. Some people are good at self deprecating humor; the first few weeks of medical school everyone is walking around puffed up and trying to impress - if you can make them laugh and relax, their guard comes down.
SMILE. It's attractive and attracts people to you. If you're hanging back in the corner bitter because you didn't go to Ibiza this summer, and your parents didn't get you an S Class for college graduation and you're self conscious because you're the only black guy there, it's going to drive people away. I go to plenty of parties where I'm the only white person; doesn't bother me in the least (now when they aren't speaking English that bothers me, but only because I/we consider that rude in the US). You belong in medical school and if someone makes you feel less worthy because of your skin color or less privileged upbringing, then examine whether it's truly them (which it might be - every SES level has jerks) or your reaction that's to blame.
You don't need to befriend everyone in your class but charm a few and that will begat more. Smile, introduce yourself, ask them questions about themselves, talk about yourself (a bit), compliment them, tell a joke or make a wry observation, if they have expertise in a certain area (ie if they're local to the area) ask for advise (good haircut, gym, best burger in town, good mechanic etc). It's not that hard. Work the room, move around, meet others. Go to all the social events you can these first few weeks; make some of your own - ask a few to go out and see a new movie, invite them over for dinner at your place.
It may always feel forced for you but it does become easier with practice, I promise.