The vast majority of debris that was outside was the skin, in large part because it's thin aluminum. But yes, the physical debris is inside.

This video is clearly filmed several days after impact. There's no smoke, people are walking around on top of the rubble and the roof, and there's lots of heavy equipment around. You also don't exactly get any wide shots of the scene. All the light debris outside was probably long since picked up or relocated to clear the area.

Because this is filmed in Shaky Horror Cam and the audio has been destroyed, people want to pretend that this was like minutes after the impact. But... lol... no smoke. They sprayed water on the site for two days but you can see there's no more water being sprayed.

They'll claim there's no debris, you show them a picture of the actual main landing gear, they'll claim it was planted there. There is literally no answer for them except what they made up in their minds, believing foolish videos made by anonymous weirdos.

I'm not even going to dignify this with links to pictures of the landing gear. It's been 20 years, everybody has seen that picture at one point or another, at this point it's just willfully erasing your own memory to pretend you didn't see it.

It's funny how the most sensible 'conspiracy' you can have here is that they flew a remote-controlled airliner into the building, which would account for everything, but the conspiracy theorists reject it because missile theories are 'cooler', even though there's no evidence at all of a missile.