I also disagree with jwong. I don’t believe there is an “elitist” STEM culture. Alot of kids do STEM, yes of course, but they don’t look down on non-STEM majors at all. STEM majors tend to consist of harder classes, but that’s really the case at any engineering school.
At the end of the day, if you want study humanities at Stanford, you will do great. There’s nothing holding you back.