Complex sentence: William Indick suggests that the symbols that are commonly found in myth, legend, and fantasy fulfill psychological functions and hence are why archetypes such as "the hero," "the princess" and "the witch" have remained popular for centuries.
Split into simpler sentences: William Indick suggests that the symbols commonly found in myth, legend, and fantasy fulfill psychological functions. Hence why archetypes such as "The Hero," "The Princess," and "The Witch" have remained popular for centuries.