2.15-Why was the only begotten son of God born and placed in a manger?

2.15-
Luke 2.

2 In those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world. ² (This was the first census that took place while^[a] Quirinius was governor of Syria.) ³ And everyone went to their own town to register.

⁴ So Joseph also went up from the town of Nazareth in Galilee to Judea, to Bethlehem the town of David, because he belonged to the house and line of David. ⁵ He went there to register with Mary, who was pledged to be married to him and was expecting a child. ⁶ While they were there, the time came for the baby to be born, ⁷ and she gave birth to her firstborn, a son. She wrapped him in cloths and placed him in a manger, because there was no guest room available for them.
⁸ And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. ⁹ An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. ¹⁰ But the angel said to them, “Do not be afraid. I bring you good news that will cause great joy for all the people. ¹¹ Today in the town of David a Savior has been born to you; he is the Messiah, the Lord. ¹² This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”
¹³ Suddenly a great company of the heavenly host appeared with the angel, praising God and saying,

¹⁴ “Glory to God in the highest heaven,
    and on earth peace to those on whom his favor rests.”

Who would have expected God, the creator of the universe, would have sent His only begotten son into the Universe on earth in a room with livestock and his first bed a manger?  

His arrival announced to humble shepherds when he could have landed him in a palace and had the royalty to announce His birth.

God wanted to identify with us as humans on the lowest level so that anyone could approach Jesus as their high priest who would perfectly understand all circumatnces.