Take the way we meet Arya in the very first episode. While Bran is struggling to act because he's thinking too much, Arya sneaks up from behind and nails the target.
Just like what happens in the godswood! It's also significant that the first thing Arya does in the fight against the Army of the Dead is fire an arrow, which serves as a nice reminder of her introduction.
In Season 1, Episode 2, when Jon gives Arya Needle (which is also the episode the catspaw dagger is introduced), Arya tells him she can be quick.
And Jon gives Arya her first lesson in killing.
Which, again, this week's episode reminds us of.
Arya's whole arc has been about learning to be the ultimate killer. After Jon, she learned from Syrio Forel, who taught her how to be quick like a cat — and to say "not today" to the god of death.
Which Melisandre reminds Arya of...right before she says NOT TODAY, SIR, to death personified, the Night King himself.
Side note: Ned Stark sacrificing himself in order to save his daughters takes on a whole new level of meaning now that Arya has single-handedly won the Great War.
Moving forward to Season 3: Melisandre predicts rightfully that she and Arya will meet again.
Little did we realize at the time just how significant that BLUE EYES remark would be.
Arya went on to learn from the Hound, who taught her to find gaps and weak spots in armor...
And how to stab someone in the heart.
Speaking of the Hound, we've long been told he had a great purpose — mostly by Ser Beric Dondarrion, who himself believed he was brought back to life for a reason.
It turns out their purpose was literally to make sure Arya Stark stayed alive through to the end.
Meanwhile, Bran giving Arya the catspaw dagger that was used to try to kill him back in Season 1 was way more important than it seemed at the time.
We even see Arya's hand-switching trick when she fights Brienne in Season 7.
And in the Season 8 premiere, Arya sneaks up on Jon in the very spot she later sneaks up on the Night King.
Basically, there have been lots of little moments of foreshadowing throughout the series.
Our small stabby murder child really saved the world.