It's not a theory, it's a recognized reality in historiography.
The Abrahamic religions are called the Abrahamic religions because all three claim either actual hereditary (Judaism and Islam) or spiritual (Christianity) descent from Abraham. Abraham was said to be descended from Noah (it was important, but an often failed effort, for the writers of scripture to keep all their ducks in a row). He was said to come from Ur of the Chaldees. The Chaldeans were a Semitic people who briefly ruled Babylon. Essentially, the chronology doesn't work if Abraham was supposed to be a Chaldean, but it does work if he were Sumerian. Since the Chaldeans are known to us from Hellenistic sources, it's entirely possible that this is a designation of a Sumerian tribe.
Talking about Babylonians is essentially meaningless. About 4000 years ago, the Akkadians (a Semitic people) founded Babylon. It was overrun by the Assyrians, briefly by the Chaldeans, and then finally by the Medes and Farsi (the Persians). Who the Babylonians were depends upon what time in hsitory you are referring to. The Jews had been carried off into captivity by the Chaldeans about 3000 years ago. It was not uncommon for whole tribes to be taken into captivity for use in completing monumental architectural projects. When the Medes ovrran Babylon, the Jews were allowed to return to western Palestine. At that time, they revised the Pentateuch, and as there is no evidence of these stories previously, and as they wrote now in Hebrew rather than Israelite script, it is very likely that they incorporated the flood story and several other lively and entertaining stories they had picked up while living near Babylon (see the Gilgamesh Epic). They returned to Palestine and revised the Pentateuch between 2600 and 2500 years ago.
No matter how you slice it, there just isn't any good evidence that the Jews were important economically, socially, militarily or even religiously, until the Arameans came along. They spread confessional Judaism throughout the middle east and into central Asia, eventually carrying it to China, just as they would subsequently do with Nestorian Christianity. The evidence for this is reinforced by Marco Polo's narrative. It is because of the great commercial and economic importance of the Arameans that Aramaic was the lingua franca
of the region at the time when the putative Jesus was alleged to have lived. The nasty stereotype of Jews as greedy, grasping, pushing commercial vultures also very likely comes from a confusion of the Arameans with the Jews.
If, as you quixotically claim, Europeans were motivated by chauvinism, why would they impute to the middle east developments which archaeology has shown occurred in Europe either first or contemporaneously with those same developments in the middle east? You're not making sense here.
For the religiously obsessed Christians of the 18th and 19th centuries, the idea of the Sumerians, succeeded by the Akkadians, and both being at least close cousins to the Jews, as the founders of our civilization was paramount. They were willing to fudge the evidence and ignore any contradictions to continue to peddle a false importance for the Jews in particular and the middle east in general as the fount of all civilization. As i've already pointed out, it was necessary for them to ignore China entirely to forward that thesis.