Humility is essential to all the other virtues, St. Alphonsus teaches, and Mary had humility in perfection.
Humility is the foundation of all the virtues, as the holy Fathers of the Church have taught. Let’s consider, then, how great was the humility of the Mother of God. “Humility,” says St. Bernard, “is not only the foundation, but also the guardian of virtues.” He says this with good reason, for without it no other virtue can exist in a soul. Even if a soul has all the virtues, they all will depart when humility is gone. On the other hand, as St. Francis de Sales wrote to St. Jane de Chantal: “God so loves humility, that wherever he sees it, he is immediately drawn there.” This beautiful and so necessary virtue was unknown in the world. But the Son of God himself came to earth to teach humility by his own example. He willed that in this virtue in particular, we should endeavor to imitate him: “Learn from me, because I am meek and humble of heart” (see Mt 11:29). Mary, being the first and most perfect disciple of Jesus Christ in the practice of all virtues, was the first also in the virtue of humility. By it she merited to be exalted above all creatures. It was revealed to St. Matilda that the first virtue the Blessed Mother especially practiced, from her very childhood, was that of humility. —St. Alphonsus Liguori, The Glories of Mary
Thigpen, Paul. A Year with Mary: Daily Meditations on the Mother of God (p. 185). Saint Benedict Press. Kindle Edition.