>>892I'll be honest i'm no demolitions expert, so i can't really say.
My expectation is that if significant irregular damage is done to a tall building like that, the top part would begin leaning in one direction. Since buildings aren't very flexible, it would sheer off and then the top part would slide off one side, leaving behind a building-"stump".
Of course this assumes a regular steel box-frame, which the WTC did not have, it had a strange thing going on with a center column and all the rest of the steel frame was in external walls of the building. So that might explain why the towers fell the way they did, i don't really know.
There was a smaller building near by the towers that also collapsed, and that seemed really odd, since it didn't appear to have been damaged all that much.
Since we don't really have 1:1 examples to compare this too, because airplanes usually avoid collisions with buildings, it'll remain speculation.
However since this attack ended up being the political justification for launching several wars, a political conspiracy seems likely, meaning that they might have knew the attack was going to happen but instead of foiling it they let it go through for political expediency of war mongering. I think wars generally get started by lies, so you are correct to suspect the 9/11 narrative to be un-trust worthy.