We learn about the greatness of Moshe Rabbeinu from another aspect when he is told to take vengeance against the Midyanim. He is told that once he does this, he will die. One would think he has the perfect excuse to stall so that he could live longer. Nevertheless, Moshe did not hesitate in fulfilling Hashem's wishes even though it hurried his own demise. Moshe taught us that fulfilling the word of G-d takes priority over all else.
We also learn how devoted Moshe was to עם ישראל by asking Hashem to find a worthy successor. He said that Israel's future leader should actually lead. Rashi says that such a leader should be the first to go out to battle instead of those kings who send their army to fight while they remain comfortably in their kingdoms.
The new leader should be one who understands the people and their whims. He needs to realize that there are many differing personalities among the people, and each needs to be reached in their own way.
Moshe's devotion to G-d and the Jewish people show why Moshe was the greatest man that ever lived.