Even though it arrived in theaters just six weeks after the release of Iron Man, The Incredible Hulk is viewed as an outlier in the Marvel Cinematic Universe, and the studio wouldn’t mind at all if you pretended that it never even happened. Born from Marvel’s collaboration with rights holders Universal before they truly struck out on their own, the events of the movie were quickly swept under the rug and never mentioned again.
In fact, if it wasn’t for William Hurt making a surprise return as Thaddeus Ross in Captain America: Civil War, you could remove The Incredible Hulk from canon completely and it wouldn’t change a single thing about the MCU. Edward Norton was replaced by Mark Ruffalo and Louis Leterrier’s movie was never mentioned again, nobody else from the cast appeared in any of the franchise’s other projects, and none of the story threads hinted at were ever picked up.
Even in the awkwardly shoehorned in post-credits scene with Robert Downey Jr., Ross is the only character that he shares the screen with, so if Hurt had either declined the opportunity to return or there was no role for him in the scripts for Civil War, Avengers: Infinity War and Endgame, the MCU would simply continue to roll on without even acknowledging the fact that their second-ever movie existed, and it wouldn’t have made a shred of difference to the Infinity Saga.
Ruffalo’s Hulk still isn’t contractually allowed to headline his own solo film, and his time as Dr. Banner may be drawing to a close as it seems that the original Avengers are slowly being phased out in favor of the new recruits, so even if the MCU continues to dominate the industry for another two decades, we’ll still be looking back on The Incredible Hulk as an anomaly, and possibly the character’s only standalone entry in the franchise’s entire back catalogue.