The appearance of the shepherds, therefore, brings to mind both Jesus’ earthly and heavenly origins. They also given confirmation to confirmation to Mary and those with her (e.g., her in-laws) that the child is who Gabriel said he was.
An alternative way of reading the encounter between teh angelic hosts and the shepherds is that the army of God is making an announcement of war and rebellion against the powers of this world and specifically against Caesar Augustus.
Read through the concluding chapter of Luke’s gospel and see how Luke brings his opening full circle. Luke begins and ends in the Temple, and begins and ends with the understanding of Jesus as the fulfillment of the Scriptures.
These first two chapters in Luke provide a bridge between the Old Testament and the life of Jesus. Therefore, these first two chapters are written in the style and motif of various stories in the Old Testament creating this continuity.