You can't completely rule it out but it is a long shot otherwise it would have happened before. It would be trivia-like noteworthy, and perhaps historically substantive if the rookie quarterback was also the Super Bowl MVP. What if the rookie quarterback was a backup and came off the bench because the starting rookie quarterback became ill or got injured early in the game?
Nothing can ever be completely ruled out. Otherwise, no record would ever be broken, lol. However, history should not be necessarily ignored as well. It tends to teach since it is very often relatable to what is happening in the present.
That is a good hypothetical worthy of sub-discussion. That said, it is a scenario (if I am reading it correctly) involving a rookie quarterback doing his part and excelling in a single game (e.g. the Super Bowl).
Quarterbacks are a single vital cog of their machine. Teams go far if he, his teammates, the coaches and front office all do their jobs consistently better than their opponents.
Veteran quarterbacks have been that essential cog for teams that strive for the postseason. Reach the postseason. Push through the postseason. Reach the championship game. And for that single team that has everything fall perfectly into place, win it all.
Despite the odds, that goal is what Washington is attempting to do with rookie Jayden Daniels at quarterback. Playing a rookie quarterback was that franchise's goal from before they drafted Daniels. As Jerry Jones would say, Washington was 'all-in' on a rookie possibly leading its team and go all the way. Succeed or fail (history suggests it would fail before it was conceived), that was their plan.
Jones was all-in on a rookie quarterback being his team's cog in 2016, except a rookie quarterback-led team was
not the plan. The original plan was for a
veteran quarterback to be that cog but the veteran was injured in preseason. The backup plan was hoping (as all teams cling to when the starter gets hurt) was for the backup veteran to be the replacement cog but the backup veteran was injured.
Thus, the backup's
backup, and rookie, quarterback was the adjustment for Dallas' plan. And the rookie quarterback performed historically well. And his teammates and he did not perform well enough after reaching the playoffs.
Super Bowl history suggests every cog of any team must work optimally well to reach and/or win the Lombardi Trophy. In the past, every quarterback cog has been a veteran. That includes Earl Morrall. Jeff Hostetler. Doug Williams. Jim Plunkett. Trent Dilfer. Tom Brady. And those are just the veteran
backup cogs on eventual winning Super Bowl teams I can remember. The same has held true for Super Bowl runner ups also.
Washington has banked on bucking history. The world will witness whether its
plan will pay off. One thing is certain, though. In 2016, a veteran quarterback was available for a postseason run but Jones'
gamble (not the original plan) did not.