well aside from the fact that they work, why exactly?
I don't know if you realize just how amazingly hard it is to control the Mississippi River (which routinely every decade massively overflows its banks), so Venice on the Mississippi seems unlikely
The Native Americans did practice ecological engineering on a massive scale (read the book "1491" sometime), but some things are set by biology. Unless you have had to carry firewood any distance, you really don't understand what a pain in the neck that is.
Central Africa is on the trade routes from Europe and Asia, with gold and other items (including slaves) making their way to Europe and the Middle East in Ancient times. It is on the periphery, but it is not by any means isolated from Europe at any point in its history.
There is no "controlling" being done. The Baure lived on a flood savannah with no hope of stopping it. They like the floodplain hopewellians adapted by creating mounds but went one step further by mounding roads and using the resultant canals for continued travel into the "dry" season allowing aquaculture and aboriculture to take form.
These novel and highly innovative forms of urban planning and engineering go beyond that of the very generalist text that is 1491, but it also shows an alternative. Eurasian city building didn't happen because it was the absolute best. Templates were made based on a number of variables and that was replicated elsewhere with many negative consequences that we see today.
I have carries firewood/stones/geophytes/acorns from mountains in bulk. I've also rowed full canoes and can say the later is much easier on still water.
Thirdly while central Africa later developed trade routes to the Indian littoral by and large the extensive routes were those of internal trade done completely on foot and were repeated by Arab and European invaders.
You don't even seem to know what you're talking about with your comparison of Venice to Baure topography and hydrology, neither the similarities in Mississippian riverine cycles.