The story of Samuel is all about human beings thinking they know better than God and in their arrogance and pride He has to show them differently.

“All the elders of Israel assembled and came to Samuel at Ramah and said to him, Behold, you are old, and your sons do not walk in your ways; now appoint us a king to rule over us like all the other nations. But it displeased Samuel when they said, Give us a king to govern us.

And Samuel prayed to the Lord. And the Lord said to Samuel, Hearken to the voice of the people in all they say to you; for they have not rejected you, but they have rejected Me, that I should not be King over them.

According to all the works which they have done since I brought them up out of Egypt even to this day, forsaking Me and serving other gods, so they also do to you. So listen now to their voice; only solemnly warn them and show them the ways of the king who shall reign over them.

(1 Samuel 8:4-9 AMPC)

God raised up a king after his heart to replace Saul. David was a humble shepherd boy who in spite of his weakness and failures would represent the coming King God would bring to rule the Earth in a future promised Kingdom that would be ushered in by a descendant of David. This king would be referred to as the “Son of David.” He would fulfill all the promises given to Abraham.

Later in the story, the prophet Isaiah would put it like this…

For to us a Child is born, to us a Son is given; and the government shall be upon His shoulder, and His name shall be called Wonderful Counselor, Mighty God, Everlasting Father [of Eternity], Prince of Peace. Of the increase of His government and of peace there shall be no end, upon the throne of David and over his kingdom, to establish it and to uphold it with justice and with righteousness from the [latter] time forth, even forevermore. The zeal of the Lord of hosts will perform this.

(Isaiah 9:6-7 AMPC)

Again later in the story the prophet Micah would also say…

But you, Bethlehem Ephratah, you are little to be among the clans of Judah; [yet] out of you shall One come forth for Me Who is to be Ruler in Israel, Whose goings forth have been from of old, from ancient days (eternity).

(Micah 5:2 AMPC)

Notice the place of His birth and the titles given to Him as well as the reference to this individual being upon the throne of David. These prophesies tie David directly to the Messiah, the promised future King of Israel who would rule forever. Israel would get their human King but He would be a combination of man and the divine.