One macro aspect of historical change to keep in mind is the sedimentary layer-nature of accumulated development. We have layers upon layers of persistent change over centuries and even millennia, interacting well into modernity. Technologies, techniques and traditions, debt and finance forms, philosophies, mathematics, political and legal concepts, cultural and organizational forms, stores of information and memory, and so on.
Large portions of this are destroyed as a given civilization declines and falls, especially those forms closely coupled with the cultural life and perceptions of that particular civilization, but then there are plenty of other forms that are transferrable, especially certain "hard", abstract and general, and non-perishable technologies and traditions. Wheels, aqueducts, and monies are difficult to "un-see" or phase out after they have entered into usage for example.
This is not a completely linear progression to be sure, with documented cases of independent inventions around the world taking place in different cultures which are attempting to solve similar problems and come to similar conclusions, such as with various forms and instruments of money, political and cultural organization, infrastructure, and warfare.
But a rising power may salvage more tangible knowledge, traditions, and techniques from the written stores of a fallen one for example, carrying on their own translations of inherited histories, philosophies, political and legal traditions, financial instruments, mathematics and so on out of reverence and pragmatism.
And much of these developments are cumulative and synergistic once they are layered atop one another. Once something has already been done, there is a little less room to do it again, so change and innovation must spread out. "Reinventing the wheel" is regarded with befuddlement and even contempt, so what works continues to be put to use, accelerating that given facet of daily production, as the thing no longer has to be developed through trial and error, freeing up time and resources to explore other avenues.
The technology advances and we have more durable and lasting knowledge stores for example, and we know much more in higher fidelity. It still remains to be seen whether all of this layered development can support itself in perpetuity however, especially as the power and reach of the development itself produces more global and catastrophic harms alongside its benefits.
