Structuralism is a theory in that no story is truly original. An example of this can be West Side Story and Romeo and Juliet. Though original characters and dialogue, the story line is all the same. This theory is a plot based theory that relies on a strict structure that almost every work of literature seems to follow, almost like a distinct formula where no matter what the characters, setting, and dialogue you include, there is already a similar story. This theory can be problematic however in that because it is so based on plot it does not discuss the characters and how they evolve in the writing which can differ from similar writings. This theory is on the opposite end of Marxism in where that theory is character based only, this one is solely based on what story is similar to the one being discussed and does the plot differ at all. 

Claude Lévi-Strauss was the author who proposed the theory or paradox which explains how so many myths and legends in different cultures are almost exactly the same.

Northrop Frye used his impact to reject open ended writing and attempted to make literature more clean cut and to the truth leaving less up to the reader and more up to the author for how things are interpreted.