The first verse of the first chapter of Matthew begins with the "genealogy of Yeshua the Messiah, the son of David." The next five verses trace the genealogy from Abraham to David's father Jesse, and then from Jesse to David.
The next ten verses trace the genealogy from David all the way down to "Yeshua, who is called Messiah." Twenty-eight separate individual's of the Davidic House are listed in this genealogy.
Clearly, David is the hook on which this entire introduction of Yeshua the Messiah is being hung by Matthew.
Why?
Most would say that is because Scripture says Messiah would be born in David's line.
That is very true, but again, why?
Why was the Messiah to be born in David's line?
It is this deeper question that needs to be answered for us to grasp the reason the line of David was seen by Matthew as the highest priority, listed before anything else in the first Gospel.
To grasp the answer to this deeper question we need to consider David, David's line, and the Davidic Covenant - all of which played an essential role in Israel long before the coming of Messiah, and continue so forever after.