God chose the shepherds because they were common ordinary people, like you and me. Except for Matthew and Paul, Jesus chosen Apostles were common men, fishermen. They were probably products of little or no education. In Jesus time, the elite of the Jewish power, the rich, the Pharisees, the Scribes, the Jewish Royality (Herod and the High Priests) would have nothing to do with Jesus. In Scripture, over and over God rejects the proud and powerful while accepting the meek and humble:
Proverbs 3:34 34He mocks
proud mockers
but shows favor to
the humble and oppressed.
Matthew 23:12 12For those who exalt themselves will be humbled, and those who
humble themselves will be exalted.
James 4:6 6But he gives us more grace. That is why Scripture says: "God opposes
the proud but shows favor to
the humble."
Luke 14:11 11For all those who exalt themselves will be humbled, and those who
humble themselves will be exalted."
So, that's why God announced the birth of His Son to the lowly shepherds. And keep in mind that the most powerful/rich/proud of the Jews, their leader King Herod, was seeking Jesus, sending His soldiers to kill Him. But the lowly shepherds came to see and worship Him.
The world turned upside down.