I have always been baffled by the word “deep” when applied to a person. I think it is used to describe someone who says cryptic and abstract things about themselves; they use words and phrases that sound authentic but they are constructed to have an effect. “Deep” people are attempting to differentiate themselves from the herd; they want to sound exotic and mystical. They want the words they use to have multiple meanings that are difficult to pin down precisely.
The phenomenon that drives the confusion around understanding ourselves and others—the mysticism that surrounds romantic descriptions of personalities—is related to the language we use to discuss and describe what ourselves and others do. Complex words are really meant to summarize the observation of multiple human behaviors that are all similar and collectively can describe those similar behaviors. For example, 10 similar behaviors describe a supervisor’s statement, “Jim is unenthusiastic about his work.”