Selective colleges don't matter, just don't go to a community college. And selective high schools (?) don't mean anything past a college application, and that's only if you're going to one of those high-roller 30k a year private highschools.
I went to a very costly private college for 1 year. Then, I switched to a state school. Peers from that college who wanted to do medicine never did it. I did.
At a state school, you can hustle. You can go talk to research professors. You can shack up with a nice little research assistant program. You can get publications. If you go to a liberal arts school on a smaller scale that costs twice as much, you're not going to be able to do that in any significant depth. You want a place with bigger names in research, and ties to hospital systems to more exposure to that and easier shadowing opportunities to pop up.
Here's a little advice though- seeing as how you're in highschool, go in with an open mind. Medicine is not what highschool students think it is. And osteopathic medicine = allopathic medicine for all practical purposes at the moment, unless you want to dive into some OMM. But MDs will probably have the option to do that in the next couple of years. So go somewhere you'd feel comfortable spending at least the next 4 years of your life at, and somewhere you feel like you could thrive in, regardless of your career choice.