As I recall in the original, “Jed” was no longer a “high-school” kid either.
I could be wrong.
He wasn't. They didn't say, but I'd put his age at 19 or 20.
It's doubtful that I'll go see the remake. I'll bet money that the Communists are all guilt-ridden, sympathetic characters who are "Just Following Orders", the "Wolverines" are a correctly-diverse group of kids, and the bad guys are all Straight White Males Conservative American Males.
Just guessing....we'll see in a year.