I'm a medievalist, and study an era where patents were unknown and people copied everything.
Me too! By training anyways. I studied under Kevin Kiernan at the University of Kentucky and worked on the Electronic Beowulf (amongst other projects).
You mention that everything was copied, and this has also lead me to my train of thought as well. We wouldn't have ANYTHING were it not for blatant copying. Chaucer (and every other medieval author) would have squat were it not for blatantly ripping off other people's work. Large chunks of his work are word for word copies of his predecessors (particularly the Italians). Virtually every Greek statue we know is not a Greek original, but a 1:1 Roman copy. And these are some of the greatest works of art the world has ever (or will ever) see, and none of that copying stifled anything. If anything, it allowed artists to take their craft further and advance their respective cultures.