> b) The transition to agriculture (which triggered the technology explosion) took a long period of luck, including groups of people living in a floodplain for a long enough time to breed plants that were suitable for agriculture. Note that this was an extremely rare thing, in that it probably only happened ~4-5 times in human history and spread everywhere else.

The accepted origins of agriculture keep fluctuating, but there's unambiguously at least 8 origins and maybe a dozen. The unambiguous origins are Mesoamerica, South America, Mesopotamia, Indus/Ganges, and China (all of which are also clearly independent origins of civilization), as well as North America, Ethiopia, and Papua New Guinea (which don't clearly form independent origins of civilization, although note word order in that phrase). There's probably more origins as well.

In general, a lot of early civilization development is one of those things that was traditionally understood to be difficult and everyone cribbing off of the one guy who did it (kind of like how the Industrial Revolution is generally though to have happened), but the more people started digging into the research, the more endogenous its evolution appears: independent reinvention of the Neolithic Revolution seems to be the norm, not the exception.