It's not an amonmaly, it's something that happens in every accident, explosion, disaster, etc. There has never been any destructive incident where some things remain and others are destroyed. So you somehow feel that for the first time in history either everything should be destroyed in a place crash, or nothing should be? That would be unheard of yet you seem to expect it. Why is that? Why is it strange to you that some things survive and others are destroyed? Why do you only find it strange in this case and not every other?
Do you claim conspiracy theory when a tornado strikes destroying homes and leaving other homes across the street perfectly in tact?
The irony of your claim is that not long after 9/11 there were other incidents of plane crashes where exactly the same thing happened. The plane would get destroyed, but papers and ID would be found. Yet you only claim it odd in the case of 9/11 and no other instances. Why again is that?