The Summer of Heroes Showcase is an attraction like The Path of the Jedi attraction in Disneyland. The Path of the Jedi which was a pretty much good lead in to The Force Awakens in that if you hadn’t seen the Star Wars films or hadn’t seen them in awhile it basically was like a fun cliff notes version of the original trilogy.
The Summer of Heroes Showcase attempts to do the same thing with the MCU (Marvel Universe). It basically gives you a glimpse into the Marvel films with some good fun clips. Unlike the Path of the Jedi which was edited with purpose and leads right up to the events of Return of the Jedi, this Showcase just seems to random. It doesn’t do a good job of connecting the MCU leading into the next series of films. If you are a fan of the MCU–you may still enjoy it because it brings up good memories from the films.
As a bonus to the film footage itself–they did have some of the cool costumes of the some of the Marvel characters in the waiting area before the feature.