It depends on the particular fields and the specific skills they require. I’m a math major who can’t write very well, so I probably get better grades in my math classes than I would get if I took a bunch of English classes. On the other hand, I would probably have more success with English than electrical engineering because I don’t like labs, I don’t have good intuitions about physics, and I’ve never been the kind of person who likes to take things apart and see how they work.
Why do you think your STEM classes are easier than your humanities classes?