Ivy league admissions officers, actually just admissions officers in general, do care about the school you come from but not because they're looking to get students from top high schools, almost the opposite in fact. AOs care about your school because they need to know what is available to you as a student. It's not fair to directly compare a student who goes to a top high school and has access to 20+ AP classes, amazing teachers, and high quality EC opportunities to a student who comes from a tiny school, has no AP classes, and where EC opportunities are hard to come by.
As long as you are pushing yourself academically and doing well at your school, that's the important stuff. The AOs will be given info about your school, typically called a school profile, so they'll know how you stand against other students at your school and then will compare you to other students in context. You won't be penalized for going to a "non-elite" school!
