1. Matthew: Christ presented as the King of Israel. "Behold THY KING" (Zech.9:9).
2. Mark: Christ is presented as The Servant of Jehovah. "Behold...MY SERVANT". (Zech. 3:8).
3. Christ is presented as The Perfect Son of Man. "Behold THE MAN". (Zech. 6:12,13).
4. Christ is presented as The Eternal God. "Behold YOUR GOD." (Isa. 40:9).
Matthew establishes His Royal Rights to the Throne of David. Mark gives no genealogy. That would not be an issue with a Servant. Luke establishes His full human and Natural Lineage. All the way back to Adam. John also presents no genealogy. He is traced back "from everlasting" The Eternal God.
There are four gospels because they represent the four-fold picture of Jesus Christ's earthly life and ministry. Perfectly God and perfectly Man.
That makes no sense in any way, shape or form. To begin with, 3 is the usual number. Perfectly God and perfectly man is 2, by the way. Also, there is only one Genesis. One Revelation of John. One of everything in between except for the Gospels.
If the Gospels were complete and exactly correct, then there would be one. One account of the Sermon on the Mount. One account of the Crucifixion. One account of the Resurrection.
By the way, is Joseph, the husband of Mary, the son of Heli, or the son of Jacob? Enquiring minds would like to know. Hint: Matthew and Luke.