Asking if Job was a real, historical person is something like asking if there really was a boy who cried wolf once too often. It is like wanting to know how old the Good Samaritan was when he came upon the wounded Jew. These questions miss the point.
The important thing about the book of Job is the message it conveys: Have faith and trust in the midst of trouble. With that said, R. Potter, O.P., in A New Catholic Commentary on Holy Scripture, writes: "It is reasonable to hold and there is ample evidence that Job was the name of an ancient patriarch, sage or hero in Israel and in yet older traditions of Mesopotamia and Egypt."