Speaking through Jeremiah the prophet, God promises the coming of shepherds “who will shepherd (the people) so that they need no longer fear and tremble.” Specifically, a king will arise who "shall do what is just and right in the land." Mark portrays Jesus as the fulfillment of this prophecy, the teacher of those who were “like sheep without a shepherd.”
The image of shepherd presents a problem for some, who resent being compared to sheep, those docile animals instinctively following the directions of the shepherd. The focus of the biblical image of the shepherd, however, is not on the docility of the sheep but on the care that the shepherd provides.
The shepherds of Israel are being castigated by Jeremiah because they “have not cared” for the people. Jesus, on the other hand, feels for the people and will eventually give his life for them. Psalm 23 is a great tribute to God as shepherd, who watches over us so that “there is nothing (we) shall want.”
Jesus is, to use the words of Jeremiah’s prophecy, “The Lord our justice, and it is he who is our peace.” Jesus is our justice and our peace through the cross and his blood, so there is nothing sheepish about Jesus, the shepherd, or about his followers.
Notice that in Jeremiah’s prophecy God “will appoint shepherds,” not just “a shepherd.” God appoints all of us Christians to care for God’s people.
The Church is a sheepfold whose one and necessary door is Christ [Jn 10:1-10]. She is a flock of which God Himself foretold that he would be the Shepherd [cf. Is 40:11; Ez 34:11 ff]. Although guided by human shepherds, her sheep are nevertheless ceaselessly led and nourished by Christ himself, the Good Shepherd and the Prince of Shepherds [cf. Jn 10:11; 1 Pet 5:4], who gave His life for the sheep [cf. Jn 10:11-15].
Vatican II, Constitution on the Church,
1964: paragraph 6.