This question is somewhat difficult to answer in the sense that it's not really clear what you were discussing with your acquintances. Certainly there are remnants of buildings almost everywhere prior to 2800 BCE, including buildings that precede the neolithic. The neolithic itself of course originated in the Levant, where you have iconic sites like Jericho and Çatal Hüyük, which obviously contain many remnants of buildings, though none of them in strictly pristine condition; meanwhile among the earliest urban centers of Mesopotamia, Eridu has a continuity of temple building from 5000 BCE on.

Concerning that Wikipedia list, the issue with it is that it uses a very particular and somewhat arbitrary definition of the word "building" that, perhaps accidentally, rules out almost everything else. Primarily, it's a list of structures with multiple fully walled rooms that are largely intact. I suspect that even with the criteria that list uses, it would be quite flawed, but that's not actually very important; the point is, to be included on that list, the building would have to be constructed of materials and with techniques which would survive 6000 years intact (which excludes wood and brick structures), be situated far enough from population centers and the like where the building would almost inevitably be built over or broken down for scraps, and be researched thoroughly enough that it can be reliably dated.

That being the case, the definition they're using leaves us almost exclusively with burial sites constructed of massive stone, particularly tomb chambers inside tumuli, while narrowly excluding the temples of Çatal Hüyük, the iconic Tower of Jericho and the ritual enclosures of Göbekli Tepe, which date to the 9th millenium BCE and represent at the moment the earliest known monumental architecture. Setting that definition aside, though, it only really demonstrates that in Neolithic Europe there was a burial custom favouring stone chambers inside large artificial mounds.