To what extent could you argue that the Romans created their own civilization?
It is certainly possible to argue that Rome largely created its own civilization. This is not to say that it was solely responsible for the creation of that civilization. Rome did borrow heavily from other cultures. However, it built upon what it borrowed, thus doing much to create its own civilization.
Rome clearly did borrow a great deal from at least two civilizations that went before it. One of these was the Etruscan civilization. It was the Etruscans who built Rome into a real city in the time of the Roman monarchy. The Romans borrowed the toga from the Etruscans. They borrowed the fasces as the symbol of authority from them. The Etruscan alphabet (which came from Greece) was modified to become the Latin alphabet.
The other major source of Roman civilization was the Greeks. Roman literature came from the Greeks. So did Roman philosophy and Roman drama. Essentially all wealthy Romans had Greek slaves to tutor their children. Greece is seen as the influence that made Rome more civilized.
However, it is still possible to say that the Romans created their own civilization. It was the Romans who managed to create a system of government that was efficient enough to hold a large empire. It was the Romans who synthesized the Etruscan and the Greek influences into their own culture. The Romans clearly borrowed from other peoples, but they took what they borrowed and made it into something grander and more lasting than what either the Etruscans or the Greeks had managed.