Lesson 1) Airport Security Sucks
Obviously the terrorists that won the day in this scenario were only able to do so by exploiting our key weakness, which was airport security. Cue massive overhauls of airport security which do maybe a little good but mostly probably just piss us all off.
Lesson 2) Arabs are dangerous
This isn't a lesson, this is historically biased BULLSHIT from a culture of fucking Crusaders who can't stop fighting the same fucking war.
Lesson 3) America is hated
I'm going to leave this lesson here because it's one we haven't truly grappled with yet and honestly I feel it deserves the most reflection.