What classes in college do you have to take to become a musician?
You can find out by looking at the curriculum of anhy fine arts school. Even in Fine Arts not all the classes you take are for music; there are also some general education classes that are required as well. For musicians, you will specialize in some classes based on the instrument you are proficient with and the type of music you want to perform.
Then there are performance classes to take, music theory classes, and music history, to name a few.
Bruce Springsteen did not have a college degree. He bought a guitar at 13 and friends taught him to play and helped him land a lead singer position with The Castles.
There are many musicians and songwriters making big bucks who have no college degree in music. Now, if you want to be a teacher or a classical musician, go to college and get a degree. Otherwise, you can teach yourself to play any instrument out there and you don't need a piece of paper hanging on the wall to tell you that you can.
The classes you take in Junior High are not a factor. The classes you take in high school do not really affect your ability to become an attorney. And, believe it or not, the classes you take in college don't really matter. Law students can have just about any degree and go to law school. I was an engineer with no thoughts of law school when I got out of college.