Worrying about adult responsibilities is kind of a slippery slope. In an ideal world (and how I plan to raise my kids), small humans would be gradually taught the life skills they need as they get older and their brains mature (specifically money, but also about relationships and other stuff). That being said, the frontal lobe (the part of the brain for making rational decisions) isn't mature until you turn 25. So there's that as well.
I take issue with you saying that language/math are the only important things taught in American schools. The other classes are important as well. Some of them are indeed a snoozefest, but you should still take the classes, since, like vegetables, they help you grow as a human. Take the classes I took while in high school for example. I know I'm probably an aberration because I went all in on APs to improve college chances, but bear with me. And I know that I hated some of those classes in high school. But frontal lobes are going to frontal lobe.
Band - Not important in the short term unless you plan to be a musician (which is hard). But playing an instrument gives you a boost when it comes to applying for colleges, especially if you placed in competitions, or where high up in the hierarchy (like me, first chair for all of high school). Fairly certain there are also studies on the correlation between smarter and playing an instrument since you have to multitask (read sheet music, manipulate fingers, blow air/move your arms/move your feet, and doing that all within the same instant).
Math - Being able to use your brain for logic (which is what math is), as well as running calculations in your head is important. Maybe you don't really need to calculate your height after jumping off a rope swing, but you certainly need to know what momentum and inertia are and how they might affect you in a car.
Science - you literally keep aquariums. Knowing about chemical interactions could save your life (you don't mix bleach and ammonia because they make chloramine gas which kills you). Understanding how the world goes, as well as what fuels the world, allows you to be relatively well educated and understand things better when stuff like, oh, say, a pandemic, happens. Knowing how pathogens spread and are prevented (herd immunity!) turns out, is super important.
US History - it's said that those who don't learn from history are doomed to repeat it. And my god is it true. Understanding where we are today (even through what I consider to be a capitalistic and imperialistic lens) is important. You don't need to know that George Washington crossed the whatever river in whatever year it is. But knowing WHY the American Revolution happened (taxation without representation [although I think it's really just a bunch of rich dudes who didn't want to give money]) is important to realizing your role in shaping history. And also on what concepts America was shaped on
US Government - it's more than just the executive, legislative, and judicial branches! Knowing about your amendments (i.e. your constitutional rights) allows you to be a better citizen and know not only when your rights are being violated, but when others' rights are being violated.
Language classes - These give you a major step up in the job world as long as you take it seriously. Being multilingual (bi and tri lingual included) gives you a step up in the job process. It also allows you to communicate with other human beings who don't speak English. Pero, usted necesita practicar mucho o you lose it.
Health class - Some people really don't know what an STI is. Or how to make a baby. Or how to prevent the making of a baby while engaging in the process of making a baby for pleasure. Or nutrition. I take issue with how the classes are taught (sports coaches are cool, but I would have prefered having an actual health teacher), but they're important.
English class - As much as I'd love to read on forums everyday, being able to practice critical thinking (which is really what English class does), as well as understand how a person uses their words to influence others around them (connotative words, denotative words, etc.), is important. It's not inherent to know what people are thinking all the time. True, you might not have to read Ayn Rand's The Fountainhead, but reading books like 1984, or Fahrenheit 451, or even The Handmaid's Tale impart ideas that I think are important in modern society.
PE - yeah I got nothing for this one.
