When I was reading the old testament, shepherds were very prominent; David and others were specifically named. But in the new testament, not as much is mentioned. Jesus would probably be taught carpentry, but I didn't see any references to that profession. Mostly fishermen are in the new testament. I just find it interesting.
There are 27,570 verses in the OT.
There are 7,956 verses in the NT.
So, the OT is roughly 3.47 times the size of the NT.
In the KJV, the term "shepherd" is used 57 times in the OT,
In the KJV, the term "shepherd" is use 17 times in the NT.
So, the term "shepherd" is used 3.35 times more in the OT than the NT.
This means that the term "shepherd" is mentioned once every 483.7 verses in the OT, and once every 468 verses in the NT.
Now, that's just numbers, but I want to suggest that one reason that one finds shepherds more often in the OT is simply because one finds more people in the OT. It's a bigger book. It tells more stories. And the principle story it tells is that of the family of Abraham, who is a shepherd. So, if it is going to tell the story of a shepherd and his family, while the NT tells the story of an itinerant preacher whose trade was that of a craftsman, we should not be surprised to find shepherds mentioned more frequently in the OT than in the NT.
Now, guess which part of the Bible mentions carpenters more frequently?
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Give up?
The part of the Bible which mentions carpenters more frequently is ......
.... the Old Testament!!
That's right. Remember, it's bigger. But strangely the OT mentions carpenters 6 times more frequently than the NT, not the expected 3-4 times more. What does this mean? Absolutely nothing.
As Qyöt27 points out, there is a change from a agrarian society to an urban one for the setting in which the narrative is told, and I think that's pretty much all there is to it. But shepherds are still very much a part of the overall culture in first century Palestine so that many of Jesus' most well known and beloved parables and stories call on that image:
True and False Prophets -- Matthew 7
Separating the Sheep and the Goats -- Matthew 25
the Feeding of the 5000 is because Jesus sees the crowd as "sheep without a shepherd" -- Mark 6
Parable of the Lost Sheep -- Luke 15
Parable of the Good Shepherd -- John 10
instructions to Peter to "feed my sheep" -- John 21
And that doesn't even include that the first announcement of the Lord's birth is to shepherds keeping watch over their flocks.