Jesus' humility is at the heart of Christmas.
In order to be acclaimed Messiah and Lord, the Son of God had to come, defeat the enemy, and lead his people out of bondage in triumph over sin and Satan and death. And that he did on Good Friday and Easter.
Grumbling is self-feeding because it obscures the light of God’s gracious, all-controlling providence.
What is superior to moral and religious achievements is knowing, gaining, and being found in Christ.