I see school as a forced opportunity for children to introduce themselves to different fields of study, to broaden their intellectual horizons, to gain familiarity with modern technology (computers, calculators, etc.), to learn how to learn and research, to practice communicating, to develop social skills, to learn accountability and to practice working with diverse peers who have differing levels of knowledge, opinions, interest and participation.
This all sounds like rainbows and unicorns and it maybe sounds like I loved school, but I'll be honest and say I enjoyed high school just about as much as the next kid. Looking back on it, had I skipped High School, I'm not convinced I would've developed a firm grasp of what opportunities and interests I wanted or could explore in life. I may have learned of those opportunities later in life, but it's hard to say. Also, for context, I grew up in a poorer urban area where kids like me were hellbent on joining gangs, stealing cars, robbing people, selling drugs, doing drugs and ultimately winding up dead from gang violence, drugs or incarceration. Hindsight is 20/20, but I'm convinced that these individuals would've followed a different, more sustainable, path had they given themselves more time to discover what subject(s) they were interested in.
With that said, I certainly didn't leave High School having mastered Physics, Algebra, Economics, Biology, Geography, History, Communications and various other subjects, but I certainly gained exposure to interesting topics like Chemistry, Literature, Geology, Astronomy, Spanish, French, German and a handful of other topics that I likely never would've explored as an adult on my own. So for me, High School is kind of a gateway drug that leads you to exploring what interests you later in life.