I think you'll all join me when I say: "All hail Arya Stark! First of Her Name, Changer of Faces, Slayer of White Walkers, Killer of the Night King, Hero of Mankind, Savior of the Seven Kingdoms, Our Queen, and in Sophie Turner's words, "That B*tch!"
I mean... could we bow down and worship her any more?!
But once we've all calmed down from the most stressful 82 minutes of our lives, there are other things to consider - namely, the fact that we're ridiculously stupid and should have seen this coming all along. You see, throughout the seven previous seasons, since Arya was a little girl who was just beginning to learn to fight in season one, there have been clues that she had been chosen to defeat the Night King - you just had to pay attention...
This was Sophie Turner's incredibly relatable reaction to Arya's triumph: Jon gave her the lesson she needed to kill the main villain back in season oneYou did good, Arya Stark! Now go take the Iron Throne, you hero!