Welp, he’s hands down the best DE we’ve had since Calais Campbell and that was what - 2007?
19 years is about as close to a generation as it gets.
If we were the only college football program over that span, you might have a point.
Here's a list of several who were similar to Rueben in college and did it in the pros for a long time:
Myles Garrett
Julius Peppers
Mario Williams
Von Miller
Calais
Here are a few more that are likely to end up on the list above:
Micah Parsons
Aidan Hutchinson
Josh Allen
Will Anderson
Here are a few that were similar to Rueben coming out of college and were busts (to varying degrees) in the pros:
Chase Young
Jadeveon Clowney
These players all played their careers during the time frame you laid out (over the past 19 years). Calais Campbell and Mario Williams may well end up in Canton, but I'm not sure they qualify as generational. As a matter of fact, I'm not sure if anyone outside of Garrett and Peppers are generational.
In my mind, generational means loosely one of a kind or the best during a generation's era. 20 years is a fair enough number. Michael Jordan, Larry Bird, Shaq, Tom Brady, Shohei Ohtani, Barry Bonds, Reggie White, Wayne Gretzky, Alex Ovechkin, Greg Maddux, Mariano Rivera and a few others are generational. Isiah Thomas, Scottie Pippen, Jaromir Jagr, Tom Glavine, Steve Garvey, Phil Rivers, Eli Manning and Howie Long were all great players in their day, but they were not generational.