How do the symbols in macbeth explain human nature?

This depends on what symbol you are referring to. Consider the floating dagger that Macbeth sees. The dagger seemingly points Macbeth towards Duncan's chambers, Thou marshall’st me the way that I was going. Does it symbolize the courage and masculinity that Macbeth feels he lacks? Macbeth really does not want to kill Duncan and needs an illusion to prompt him along the way.