“many shepherds have destroyed my vineyard.” This was a powerful word-picture in biblical times because the animosity between shepherds, especially people shepherding goats, and farmers is age old. The sheep and goats wandered the hillsides and often got into the crops and vineyards of the farmers. In this verse, God’s people are the vineyard, and the “shepherds” are the rulers, here especially foreign rulers, that trample God’s people.
The word “shepherd” was a common idiom for a ruler. That fact is in part obscured by the Christian tradition to translate the Greek word “shepherd” as “pastor” in the New Testament Epistles. If the Greek word “shepherd” were translated as “shepherd” in the New Testament, we would see much more clearly that God set “shepherds” over His people to care for them.