The resovoir was monkeys, but like ebola you caught it eating bush meat, or from scratches or bites. And it spread via truck drivers and men migrating to jobs where there were no wives, only prostitutes.
The River is one of many conspiracy theories out there. In the US They are harmless, but then the mullahs read them, forbid people from getting shots, and then kill the doctors giving medicine. And the kids die of course, but hey, the authors made their money so who cares.
I totally disagree with you that The River is an (invalid) conspiracy theory.
In addition I greatly doubt you have read it.
Presume you are aware that HIV-1 is a lentivirus (the first one discovered) meaning it has an extremely long incubation period in the body before symptoms are exhibited, accounting for why it took so long for the CDC to identify AIDS as a new illness “affecting the homosexual community.”