Avengers: Endgame might tie up some loose ends, but it also blasts a gargantuan hole through the wall of possibility for Marvel's fourth phase. Spider-Man: Far From Home is the official final movie in the Infinity Saga, and it's already giving us a glimpse at just how wild things are going to get once we dive into the new MCU era. We already know that the film hints at the possibility of a multiverse — an infinite realm in which different versions of our world exist — but there's another anomalous occurrence that the movie addresses: how the heck are Peter Parker (Tom Holland) and his classmates still in high school?
The answer is simple, albeit trippy. But let's first rewind a bit. We already know that Thanos delivers the noxious snap in Avengers: Infinity War and wipes out half the universe, including Spider-Man (and no, we're still not over his heartbreaking "death" scene). After the Avengers suffer from that devastating defeat, it takes them five years to figure out a way to hatch a victorious plan and bring back everyone who whisked into thin air.
Peter's friend Ned (Jacob Batalon), his crush MJ (Zendaya), and his nemesis Flash Thompson (Tony Revolori) are among those in his class to have evaporated in what they now call "the blip" (which is considerably less dramatic than the comic book's labeling of the event as "the Decimation"). So if they vanished for five years, it might be hard to imagine why they're still in high school. But here's why that is: anyone who was affected by the snap simply didn't age within those years. And those who were left — including the new character and high school stud Brad Davis (Remy Hii) — did get older.
When Iron Man brings back the fallen, he isn't technically creating a different timeline in which they all age before joining together at the battlefield. It'd be pretty hard for specks of dust to age anyway. Iron Man is just undoing what was carried out five years prior, but within that present timeline (with the help of Doctor Strange, of course). So in a way, time as we know it stood still — or, perhaps more accurately, ceased to exist — for the dusted. That means their physical beings are based on who they were before the snap, even though their existence resumes in a latter-day timeline.