The meaning of Mesopotamia in the Bible is of a mature society that has moved past its prime. In the modern world Western Europe is Mesopotamia. Western Europe is the sterile but highly sophisticated culture that serves as the foundation for offspring cultures. Its science and art, if not its political/economics and religion, still remains as a legacy that deserves our appreciation and respect.
In contrast to Western Europe/Mesopotamia stands the opposing empire, Egypt – the opposing cultures: variously Russia, Germany, China, the Muslim world, etc. Each claims to a vitality and a vibrancy the Western European culture seems to have lost.
The Bible is a blueprint for how a legitimate authority might govern in a mature culture that enjoys the fruits of abundance and security. Mesopotamia is the example of how not to do it. Mesopotamia is the cautionary tale that says: too much sophistication will lead to sterility and not vitality.
History can be seen to unfold as a series of Egypts vying to replace the spiritually depleted husks of a corresponding series of Mesopotamias. The narrative arc of the Bible is the narrative arc of history, writ large. The Bible situates Israel as the pivot around which the Egypts and the Mesopotamias contend with each other. Israel is a child of both Mesopotamia and Egypt. Israel plays out internally, within herself, the struggles of the contending empires and offers them first a neutrality they could trust; second, a buffer from each other they could appreciate; and, third, a solution to their differences they could adopt for themselves. The contending empires employ Israel as a defanged, safe, surrogate opposition, almost like a vaccine. The empires can use opposition to Israel as a way to develop their own cultural antibodies in their struggle with their opposing empires further away.
Here is a narrative for the role Israel plays in world history that differs considerably from the role Israel plays in the Christian or Muslim narratives, narratives that serve their own Christian or Muslim imperial ambitions. We have, as it were, two competing narratives: the religious narrative where Judaism is the Mesopotamia to the daughter religions' Egypts vs the political narrative where Israel as the safe pivot between the old, sterile but sophisticated ancien regime contending with the young, fertile, brash but clumsy, rising empire.
These two competing narratives play themselves out in two different stories of the internal struggles of the Jewish people: on the one (religious) hand, the narrative of a tired leadership that cannot muster the people as it struggles against the brash insurgents who wish repeatedly to return to Egypt's fleshpots; and, on the other (political) hand, the story of the rule of YHWH's followers who have incorporated a deeper understanding of the forces of history with which they are contending, where Joseph is Egypt; Reuven and Shimon are Mesopotamia; and Yehuda and Binyamin and Levi constitute the core of the Children of Israel. These two narratives play themselves out as, on the one hand, the diaspora narrative of religious Judaism wrestling with religious Christendom and religious Islam versus, on the other hand, the messianic narrative of political Israel wrestling with political Europe and political Arabia.