Final answer:
Most of Jesus's followers were Jews and Matthew wanted to show that Jesus traced his lineage back to the great figures of the Hebrew Bible.
Step-by-step explanation:
Most of Jesus's followers had been raised as faithful Jews and many would have to explain why they had decided to believe that Jesus was the Messiah. By beginning his Gospel with a genealogy of Jesus's ancestors, Matthew wanted to show that Jesus traced this lineage back to the great figures of the Hebrew Bible.