this film wasn't about Godzilla destroying buildings and fighting monsters like in most of the movies now. the film was focused on the fact Godzilla was a representation of something the Japanese were afraid of. Hydrogen Bombs. but in the form of a giant monster/Kaiju, the film when you watch it as a kid? you are busy watching Godzilla burning everything in Tokyo down enjoying it. as a Teen or Adult? you realize how dark and serious the tones of the movie are. Godzilla was a hydrogen bomb in slow motion. Godzilla was a metaphor for the united states with the bomb they used on Hiroshima and Nagasaki 9 years before the movie came out in 1954. the song was used in one of the darkest and saddest scenes of the film. when there they are in the hospital. the song "Prayer for peace" was also perfectly fitting for the Godzilla NES Creepy[Pasta when Zach entered a grave yard and heard a 8 bit version of the song and described it as "a very sad and powerful song".
overall, the song was a perfect composition to represent the movie's dark atmosphere overall. Godzilla represents the hydrogen bomb. and us? we are the people watching the movie understanding its realism and darkness.