Progress was slow, with milestones separated by hundreds of years. Cultures were widely separated in travel times and interactions between them relatively infrequent. Growth depended on locally available resources. A thousand years could pass between an invention in one place and its adoption or independent discovery elsewhere. An individual had a modest amount to learn, and change over the period of a lifetime was small, an amount not difficult to adjust to.
Scientists refer to such a state as one of quasi-static equilibrium.
Things change slowly through a series of equilibrium states. In the West, the disintegration of the Roman empire, first on the borders and eventually in the center, was not always immediately apparent to its citizens. For the Roman occupants of Britain, the recall of Roman administration was fairly abrupt, but elsewhere, the deterioration of imperial authority was spread over a hundred years, each decade being only moderately different from the previous one. Less obvious was that the rate of change appeared to be increasing. Change is now overwhelmingly obvious in a single lifetime.