Thanks are due to others for providing a stimulating discussion.
Emergence is a tricky concept.
It's easy to slide it down a slippery slope, and turn it into something implausible and easily dismissable. But it's not easy to delineate the interesting middle ground in between. All material properties seem to follow from low-level physical properties. This, of course, is so ubiquitous a phenomenon that it's not deeply interesting. After all, serious people do like do use the term, and they think they mean something interesting by it.