Jesus was more than a great Rabbi, but a great teacher and revealer of who God truly is. When he spoke there was a wisdom that astounded people, so his words are words of ‘eternal life’, and the words are just that because they come from his inner reality, that reality that carried and revealed the God he spoke about.
Following on from the post on sinlessness being also a growth toward a fullness of true humanity, rather than something static and intrinsic to some internal nature, I have one further suggestion.
Jesus was a GREAT TEACHER because he was a GREAT LEARNER.