Funny enough you can actually notice that some of the smart, scientists-like characters were actually always separating Quincy from Humans, Hollow and Shinigami (like Sayzel for example).
In the first place, Quincy Powers don't give you soul perception. This means that this power was originally meant for something that didn't need it, like souls itself. It's not that Quincy are Humans with Soul Perception, it's that Humans with Soul Perception (SP) can be Quincy. That is why when Uryu lost his Quincy Power, he could still see Souls, Hollows, Shinigami, but when Ichigo lost his Power, he couldn't see anything nor feel anything anymore.
It's quite interesting that SP comes along with Shinigami Powers, this might suggest that the first Shinigami were actually Living Humans.
Bach himself is the Origin of the Quincy, but he himself might not be a Quincy, in similar manner as SK himself isn't a Shinigami... maybe :P, it does seem that way. Thus him calling Uryu the last Quincy would hold true even if he was still alive.