One of the most important aspects that you are overlooking is the fires erupting from the initial impact of both aircraft. The towers continued to stand for about an hour after the impacts. The fires, spread through about 5 adjacent floors, were estimated to be burning, jet fuel fed, at well above1,500 degrees F, probably even hotter. The wall of flame that erupted behind the terrific collison of the airplanes would have disintergrated anyone standing or working within any distance available on the floors and any remains would have been jettisoned out the other side of the building after suffering enormous shearing and shredding effects
I've assisted in investigating aircraft accidents where the largest piece of any human was coin sized pieces of large bones, such as the pelvis and femur. This type of accident was usually fire free and the damage to the passengers were induced solely by the G-forces. Many of the passengers onboard both airplanes, as well as the Pennsylvania and Pentagon aircraft were never identified for this exact reason, as well as the addition of the heat...