How do we know it’s 2996 people? I used to go frequently to the basement of Tower 2 to Charles Schwab (was scheduled to go there that morning but rescheduled), and often saw homeless people down there whose families (if any) likely did not know their whereabouts. I bet some homeless were killed in the collapse and were not counted.
When the WTC Twin Towers were being finished I spent a day on the roof of the south tower helping to install an antenna. It was a strange unforgettable experience; there is nothing anywhere near by to give a perception of depth or distance -- except the other tower.
I had the (wrong) impression that I could easily just step over on to the North Tower; I did not try, however! _I__I_
(There were no homeless people on the roof!)