Star Wars: The Force Awakens closed with a heartrending death, when Kylo Ren killed his father, Han Solo, as part of his final transformation from being Ben Solo and embracing the Dark Side. Star Wars: The Last Jedi echoed that passing with a second big death: the passing of Luke Skywalker from this world into the next, having burnt the last of his life force to appear on Crait and save the Resistance. But Luke Skywalker's final Last Jedi scene was also one of the most moving of the entire film.
It helps that the scenes on Crait are beautiful, some of the most gorgeously cinematic images of the entire franchise. The white powder melts beneath the shoes of those who walk upon it, leaving behind a blood red, wet-looking surface beneath, slowly building to a stunning image. By the time the fight is over, the planet's surface looks to be streaked with blood, and the space in front of the door to the bunker like a gaping wound, even before Luke's appearance in the cave.
When Luke first steps out, we can't see he's not leaving footprints, since the white has melted away from the heat of the cannon blasts. But what we can see, after the First Order has fired everything it has upon him, is the ground there is now blackened... and he is fine.
What follows is the oddest non-lightsaber fight to ever grace the end of a Star Wars film. The standard ending to any of these films in the franchise is usually a hand-to-hand combat between Jedi and Sith, whether it's Obi-Wan vs. Vader in A New Hope... or Obi-Wan vs. Vader in Revenge of the Sith.
Director Rian Johnson uses our expectations against us. We assume this is the big Luke-Kylo showdown, where Kylo will kill him, the same way he killed Han in the last film. But there are signs that this is not the real Luke. There's those lack of footprints, for instance. And there's the color of Luke's lightsaber.
In the flashbacks with Ben Solo, Luke raises up his lightsaber, which is green. On Ahch-To, Luke also has a green lightsaber when he raises it to Rey. Rey brings him the blue saber, the one he lost at the end of Empire Strikes Back, but he rejects it. That blue saber is what she takes with her to see Snoke. It's the one that is broken in two during her fight with Kylo.
And yet, Luke is holding a blue lightsaber during his final showdown on Crait... which we should note, he never actually raises in offense, or even swings in defense, since he and the weapon aren't there.
Luke is actually still on Ahch-To, burning up the last of his life force to keep Kylo and the First Order distracted while Rey evacuates the last of the survivors on the Falcon.
He doesn't face down Kylo, because he doesn't want Kylo to have another death on his conscience. He also doesn't want his former pupil to have the satisfaction of striking him down. Instead, he disappears in a breath of air, much like we saw Obi-Wan do when Vader swung in the end of A New Hope.
Exhausted, Luke sits on the rock on Ahch-To, watching the horizon as the twin suns set. Yoda appeared to him earlier, and remarked that his former pupil was still always staring out at the horizon, to this day. It's the classic image from the very first time we met Luke, in front of Uncle Owen and Aunt Beru's, staring out as the twin sunset.
Luke died as he lived, staring out to the horizon until the end, knowing his adventure was finally done.