The humility of Moses stands in sharp contrast to the jealousy of Miriam and Aaron. The text says that Moses was very humble. His character reflected a godly spirit (see also Proverbs 3:34; Matthew 5:5).
The statement about the humility of Moses appears as a parenthetical comment (a brief note inserted into the story). It presents the truth from God’s point of view.
Some think these words may have been written by Moses. Others believe they may have been added later by an editor. In either case, the comment highlights the faithful and humble character of Moses.