Do novels REALLY have symbolism?

I have to find symbolism in the Great Gatsby and some of them are Gatsby's boyhood schedule and Daisy wearing the color white and Gatsby wearing his gold tie and silver shirt. I mean is there REALLY symbolism in that or was Fitzgerald just trying to write a story and literature teachers are just delusional? I think I'm going to write a book someday and just write at the end of it that "There was no symbolism intended in this book".