Tawnos
A guy with a bass
How did they do that?
The kid, Lyndon, did it when he tapped into the different timeline... then he specifically says to Katie that "Forrest is wrong"... and she agrees. He also says he wishes Everett wasn't the right theory... Everett is many-worlds.
I mean, it's a point that Lily's rejection of what's pre-determined might be deterministic in itself... that's a paradox. But I go back to the fact that Devs was able to tap into other past timelines, which doesn't make sense if many-worlds isn't the implied reality.