Who or what is the inspector? Do you think the writer wants us to know?

Inspector Goole is a "goul", a supernatural being. Over the course of the play, the audience is never really sure of his true identity..... but in the end, his disappearance, his accumulated and detailed knowledge, in addition to the fact that there is no "Inspector Goole" on the police force tells us that he was a being sent to expose the group to themselves.