What makes the song great is a sense of dramatic narrative supplied by Bowie vocal performance and arrangement (sort of a theme and variation with progressing intensity)
In the single edit
You have vulnerable quiet Bowie with his almost sing/speech in the first verse representing the frailty of the individual.
This progress to vocally belting Bowie representing that each individual has the power to resist or have heroism inside them.
Then you have the call and response within Bowie and the backing vocalist which to me represents the interaction between the individual and society. Maybe the individual heroism inspiring others.
Then the song ends with Bowie and the backing vocalist singing the "We Could Be Heroes" refrain together representing that the potential of heroism is present in everyone.
It's a great example of using music to support the dramatic narrative of the song in a perfectly well paced song. While the harmonies and melodies repeat itself, the arrangement and performance gives the song the dramatic narrative with it's continually developing intensities.
The perfect dramatic pacing is ruined in the album version. What's the point of dwelling on vulnerable Bowie multiple times with limited variations before reaching the climax. the song drags.
Heroes the single edit is all time classic
The album version is a flawed classic.
It is noted that King Crimson as well as Toyah/Fripp did a cover of Heroes and they both used the single edit as the basis of the cover. Perhaps Fripp was onto something there