Guardians of the Galaxy is wholly original within the confines of not just the MCU, but comic book movies in general.
Prior to 2014, even the most hardcore comic book fans were scarcely aware of Marvel’s Guardians of the Galaxy, if at all.
I was downright upset that Guardians of the Galaxy, a comic book team I, a lifelong Marvel fan, had never even heard of, was getting made into a movie before Doctor Strange.
However, Captain America: The Winter Soldier signaled a change that continued and evolved beyond anyone’s wildest expectations with Guardians of the Galaxy.