First, you are not so stupid, you just are curious because the explanations dont pass the smell test.
The WTC 1 & 2 lost their structural integrity because the central columns were cut in locations other than where the planes hit. There are pictures available that show the columns with 45 degree thermite cuts in full view. Once the central steel tube columns were cut at an angle, they could not maintain the integrity of the building. How and by whom they were cut is already known. The truth always comes out eventually.
There were concrete slabs in the pile of debris after the collapse. The pile was 10 stories high. Since most pictures that were published were taken while standing on the top of the pile, the public was led to believe that the pile was at street level. The buildings had a 6 story deep basement, that also contained much of the debris.
WTC 7 was demolished in a controlled demolition, which was pre-set. The plane that was supposed to crash into that building never took off. Did you know that there were several other suicide teams that were to be on other flights, but the flights were delayed in takeoff and boarding, and were unable to take off before the general grounding of all aircraft was declared? The plan was for at least 8 planes. Look for links detailing that there were middle eastern men in Boston, and NY that were angry and demanded that the flight board and take off and not comply with the grounding that happened after the WTC was hit. It is speculated that those other 4 planes were to crash into WTC 7, Capital Building, White House, and perhaps the Statue of Liberty.
The other WTC buildings were destroyed due to heavy damage from WTC 1 & 2's falling debris. The foundations were also compromised in those buildings since all seven WTC buildings were built in the same coffer dam and were connected underground.
You see, the ground at the WTC was formerly part of the river. The ragged shore of Manhatten was straightened over the centuries by infilling the inlets with soil. In order to build the WTC buildings, the NY Port Authority, who owns the buildings and land, had to construct a coffer dam large enough and deep enough to keep out the East River. In short, they built the buildings in a bathtub. The buildings then shared a common foundation and were connected below the street level. There was even a train and bus station there.
The collapse fo the WTC towers then compromised the other building foundations within the coffer dam, resulting in their being condemned and torn down.