In our day, family trees are not usually regarded as being very important. Some people study them for fun. But not too many people know about their distant ancestors.
In ancient Israel, it was all part of your identity and was very important. First of all, Israelites were divided into twelve tribes. You may have heard of the tribes of Levi, Reuben, Dan and Judah for example. Then they were divided into families.
So when the prophets were talking about the coming messiah, they could be very precise as to who it would be. First of all they prophesied that he would be from the tribe of Judah. Moses, writing 1500 years before Jesus, said:
“The scepter shall not depart from Judah, nor the ruler’s staff from between his feet, until tribute comes to him; and to him shall be the obedience of the peoples. (Genesis 49:10)
The prophet Isaiah, writing 700 years before Jesus told us which family he would be born into.
‘There shall come forth a shoot from the stump of Jesse, and a branch from his roots shall bear fruit. And the Spirit of the LORD shall rest upon him, the Spirit of wisdom and understanding, the Spirit of counsel and might, the Spirit of knowledge and the fear of the LORD.... The Gentiles shall seek Him.’ (Isaiah 11:1, 2, 10).
So he was from the family of Jesse, the father of King David.
So that very much limited how many people could be the Messiah. Then, add to it the fact that he had to be born in Bethlehem according to the prophet Micah (Micah 5:2), he had to appear on the scene in around 25 AD (Daniel 9:25-26), he had to go about doing good according to Isaiah and ultimately be crucified (Isaiah 61, 53, Psalm 22). He then had to have a great following from gentiles and be regarded as God. How many people in history could this apply to? There is only one, and that’s Jesus.
So many people have recognised that Jesus is the son of God, that he’s the Messiah - and and that he came into the world to save us from our sins and make sure we go to paradise when we die. If that's true, isn’t it worth following Him?