We know the stories. A Kingdom has lost all of its royalty—be it by murderous intent or by lack of birth. The whole thing is in danger of collapsing. Suddenly, a living descendant to the throne is discovered, a king by birth, and he gets to rule as king.
But it’s impossible to see Jesus as King merely by lineage. After all, it wouldn’t be surprising that David had many descendants—especially if you go through Solomon who had access to a thousand women.
Jesus, out of all David’s descendants was born of God (Matt 1:18). That is, not some matter of genetic lineage, but born at exactly when God wanted him to be born (Gal 4:4), sent from the very throne room of heaven (John 1) and born of a woman without the aid of man. His birth was heralded by angels (Luke 1:26-38) and expected by Israel as sung by Mary (Luke 1:46-55). Even his enemies would acknowledge that he is a King, even if they’re being ironic (John 19:19) but more so when they witness his death: surely, says one of the soldiers, this was the Son of God (Matt 27:54).
So we can’t see Jesus as coincidentally filling a role because he has the right lineage: it’s not possible. God was altogether involved in his inheritance and authority.
Jesus was born to be King.