OP, if that's your goal, try for it.
Absolutely. Reach for the stars.
There are people at Harvard, Johns Hopkins, Stanford, et cetera who went to community colleges.
Really? I'd guess that there are very, very few.
I'm a community college grad and interviewed at UCSF and go to a UC now. They didn't seem to mind the community college thing.
But all things being equal, schools will prefer to see the best paper application they can. They will look for well rounded, mature, experienced individuals with great scores. But at schools like JHU, you will get all these things from any interviewee anyway. JHU is one of the sorts of schools, like Harvard, where they may get so nitpicky that community college background will be a negative factor.
I only think that this happens at a very small handful of medical schools, but JHU might very well be one. I'm sure they'll overlook the CC thing if something else on your app really sets you apart, but keep in mind that your file will be among the most amazing in all of medicine. Literally.
Do not listen to the advice of people who tell you to aim lower. That's a silly thing to say. If you don't think that you're good enough to get into a high-end medical school, chances are high that that attitude will bleed through.
The people most bitter about the process are the ones most fixated on getting in to a particular medical school. Definitely aim high, but keep an open mind.
At the end of the day, there is
nothing you will get at Harvard or JHU that you can't get from many other medical schools. So shoot for a particular school, but keep an open mind over the many other amazing opportunities out there. What kind of physician you will be is based entirely on how you approach your education, not where you get it.