I don’t think it’s so reductionist as all this. If you take the appropriate prerequisites, you can major in business and still become a physicians assistant. And if you do the right internships and get the right kind of experience, you could major in biology and go into business. So I think the major question should be about which field you want to study the most in college, and a little bit about what you think would lead to the most useful or practical outcomes for you.
One thing that you should know is that in order to get into PA programs, you need to have a certain number of clinical hours giving direct patient care. The minimum is usually 1000-2000, but the most competitive/successful applicants tend to have double that. 1000 hours is about 20 hours per week for 50 weeks, or one year of half-time work. 2000 hours is, unsurprisingly, about 40 hours per week for 50 weeks (so 1 year of full-time experience), or 20 hours per week for 100 weeks (about two years of half-time experience). So that means most successful applicants have 1-2 years of full-time experience (or the equivalent) giving direct clinical care. These hours have to be achieved giving actual direct care - volunteering at a hospital or clinic is not enough. As a result, most PAs were nurses, CNAs, or EMTs/paramedics before they became PAs. Some had some other direct clinical care role, like physical therapist’s assistant or rehabilitation aide, but the vast majority worked in full-time clinical care/allied health professions first.
Basically, in order to be competitive for a PA program you are going to need to acquire that experience. At the very least, you’ll want to get training as an EMT and perhaps volunteer or work part-time as one during college. That’s one way to get the hours. Getting certified as a CNA also doesn’t take a whole lot of additional coursework (although it does take time), but you’d have to work part-time as a CNA while in college if you want to be ready to go to PA school right after undergrad. I think more realistically you’d have to get licensed as some kind of clinical care provider post-college and work at it for 2 years, then go to PA school.*
So knowing that may help you make your decision.
Neither major is objectively easier - it depends on how your mind works and what you enjoy. Most people do say the natural sciences are harder than business classes. That’s really up for you to decide. Which of the actual careers is easier is even more subjective. The Bureau of Labor Services says the average salary of medical and health services managers is $88,580, whereas for physicians assistants it’s $97,280. But a lot of factors influence those salaries. My guess is that PA salaries are more stable across your career - after you finish your MA you are likely to be quite close to that average, but your salary won’t necessarily rise that much over the course of your career if you stay in primary care. Health care administrators can start at any number of salaries depending on their role in the hospital, but if you rise to higher echelons - like VP or CEO of hospitals or hospital systems - you could potentially make a lot more than a PA.
Also, both majors do require some math, but not a lot. Biology usually requires a semester or two of calculus (and some colleges have a “calculus for health majors” class that is condensed and has less of the material). Business sometimes requires a semester of calculus depending on the school, and often a semester of finance. So biology probably requires a little more but not a whole lot more.
*Honestly, a similar career with an easier entry pathway might be as a nurse practitioner. If you are already in college, many schools have formal 3-year programs that will take you from 0 to nurse practitioner - you earn the RN along the way. There are other schools that have more informal arrangements that amount to that. And nurse practitioners have similar scope of practice to PAs.