Alright, I'm going to say this once cause you're 17 and maybe you just don't know anything yet, which is legitimate considering your age.
Adcoms dont want diversity for its own sake. They clearly believe that each and every major is legitimate, and that each of them prepares you for med school- in different ways, sure, but they all prepare you. I realize that on this website majors like biochem or *insert long scientific term here* are the be-all and end-all of med school admissions. I also understand that most people who are going to med school are good at science, and it's oh-so-much-easier to major in something you're good at.
But, 1) roughly 2% of what you did in college will come back in med school, and it will be re-taught in approximately one day. So what you major in doesn't matter. Let me repeat, IT DOESN'T MATTER. You may major in bio thinking "hey, this way I'll be better prepared for med school" or "adcoms will see how much of this stuff I know already". But adcoms know that none of that stuff is useful, so they could care less that you got an A in Plant Bio. A's are good, but the subject is ultimately irrelevant (with a couple of caveats). 2) people throw out the "well-rounded" term around constantly, figuring it's just another hoop to jump through, like the research and the shadowing and the wheeling around of invalids so you look "altruistic". Well-rounded simply means that someday, you'll be able to TALK to people who weren't science majors. The liberal arts use a different part of your intellect, and they make you smarter because of it. EVERYONE has to take pre-reqs and everyone has to take the MCAT- sciences are a given. So taking more science is fine, but taking a liberal art makes you smarter in a different way, which makes you both impressive on paper, a better writer (something the OP should really work on, incidentally), and likely more well-spoken and eloquent which is something that helps you when you have the actual MD.
As a disclaimer, I was a double major in a science and a liberal art. I didn't put the same amount of effort into the two majors cause I'm a lot better at the liberal arts stuff than I am at memorizing science facts, so those A's came a lot easier. But I had plenty of friends who failed their language classes while acing math or physics or engineering cause they just weren't great communicators. They weren't good writers. And I gotta tell you, I found some neuroscience classes I took WAY easier than the advanced literature classes I had to take. You try writing a 30 page paper that actually flows well and see how that goes.
So, I will excuse your ignorance because of your age, but please think about what you're saying. I hear a lot of bitching and moaning here about "oh I was a math major and I got a 3.2 and this other kid was an english major and got a 3.8 and why is he getting in and I'm not?". Well, first of all, his gpa is higher. Second, there is nothing inherently better about a math major because this isn't a math phd, this is med school. Sciences are just a small part of what we learn here. Also, someone with a 3.8 english gpa also did very well in the pre-reqs, meaning that he/she knows enough science to get into med school.
As a caveat, I understand that if you're a 3.9 nuclear engineer from MIT you're probably more impressive than the 3.9 communications major from xyz state college. But if there are 3 other 3.9 nuclear engineers in your class and you're all applying to the same med school, be assured that you likely won't all get in.
