Let's compare worst case scenario with Jimmy G vs Rodgers
Worst case scenario for Jimmy G is they cut him, incur no cap hit and lose no draft picks. Essentially it's as if the move never happened, they suck without a QB, and then get a top draft pick to address the position
Worst case scenario for the Jets/Rodgers is we give up a significant draft compensation, a ginormous amount of cap space, and if he's washed up then we suck and the Packers end up with an awesome 1st round pick next year. On top of this the Jets will incur Rodgers obscene cap hit every season for the next several years
Jimmy G having health risk obviously sucks, but the Raiders addressed this concern with his contract, that they can get out of at no cost if they aren't satisfied with his health.
Rodgers by far has the most upside of any QB move we could have possibly made, and if he plays his best football it gives us the best chances we've had a SB in years. He also by a tremendous margin had the highest potential downside of any QB move we could have made because of the trade/financial compensation.
FWIW it's always been clear that Carr was by far my first choice, and Jimmy G was a backup plan that you fall back to if the big boy options fall apart.