The basics: math, history, English, Writing, another language as well as an elective (there’s a whole world out there outside of the USA and knowing another language and learning about other cultures makes for more well rounded empathetic people), music also as an elective. In addition to the previous topics high school students should be taught how to budget their money, basic investments, what goes into buying a home, and what options exist for higher education. So if they choose to go to college explain how it works (I was a first generation college graduate and spent a lot of time and wasted a lot of money just taking random courses I liked instead of focusing on my major and graduating), or if they choose, after being told it’s an option, about trade schools and professions like becoming an expert electrician or a plumber or carpenter etc they can then weigh the costs of both avenues and decide for themselves.
I agree with your language parenthetical, but speaking for myself at least, my elective language course did not have this effect on me (at least that I noticed). It was actually traveling to a different country (In my case, the UK in high school, then China in college) which opened my eyes to all the assumptions I didn't even know I had.
