Who were they?

On 9/11 there were 19 hijackers involved, and all affiliated with al-Qaeda. The hijackers were split into four teams, each led by a pilot-trained hijacker and three or four “muscle men” to help subdue passengers and crew. Mohamed Atta, Waleed al-Shehri, Wail al-Shehri, Abdulaziz al-Omari, and Satam al-Suqami were the hijackers for Flight 11, the plane that hit the 1st tower. Marwan al-Shehhi , Fayez Banihammad , Mohand al-Shehri, Hamza al-Ghamdi , and Ahmed al-Ghamdi were the hijackers for Flight 175, which hit the 2nd trade center. Hani Hanjour , Khalid al-Mihdhar, Majed Moqed, Nawaf al-Hazmi, and Salem al-Hazmi were the Flight 77 hijackers for the Pentagon. Ziad Jarrah, Ahmed al-Haznawi, Ahmed al-Nami, and Saeed al-Ghamdi were the Flight 93 hijackers in the plane that went down in Pennsylvania. So, why were these men chosen? Was it because of their ranking in al-Qaeda or because of their background? Maybe it was because they were respected jihadists? That’s why Khalid al-Mihdhar and Nawaf al-Hazmi were chosen. Bin Laden himself chose these two men because they were thought of as “respective jihadists” in the eyes of the al-Qaeda leaders. Either way these men were trained in every aspect, even by Americans. The pilots themselves took a flight training course in Florida! So, who are these men? And why were they chosen? The answer is not clear, but we do know that these men were in al-Qaeda and we can infer that all of these men had been involved in some type of terrorist attack before.