Why was Jesus laid in a manger?

Why was Jesus laid in a manger?

In his apostolic letter Admirabile Signum (On the Meaning and Importance of the Nativity Scene), Pope Francis said,

Coming into this world, the Son of God was laid in the place where animals feed. Hay became the first bed of the One who would reveal himself as “the bread come down from heaven” (Jn 6:41). Saint Augustine, with other Church Fathers, was impressed by this symbolism: “Laid in a manger, he became our food” (Sermon 189, 4). Indeed, the nativity scene evokes a number of the mysteries of Jesus’ life and brings them close to our own daily lives.

Why was Jesus born into such humble circumstances?

The Catechism of the Catholic Church (paragraphs 525-526) says,

Jesus was born in a humble stable, into a poor family. Simple shepherds were the first witnesses to this event. In this poverty heaven's glory was made manifest. ...

To become a child in relation to God is the condition for entering the kingdom. For this, we must humble ourselves and become little. Even more: to become "children of God" we must be "born from above" or "born of God." Only when Christ is formed in us will the mystery of Christmas be fulfilled in us.