One main theme could be hope. Superman often represents hope in the DC universe. Another might be self - discovery as he navigates his powers and role in the world.
Soldiers can be considered real - life Supermen as well. They are trained to be strong and brave. They go to warzones or dangerous areas to protect their countries and people. They endure hardships and face great perils, just as Superman faces villains and threats to protect Metropolis. Their sense of duty and honor is comparable to Superman's unwavering commitment to justice.
Superman: Man of Steel tells the origin story of Clark Kent, a.k.a. Superman, as he discovers his powers and decides to use them to protect Earth from various threats.
The story of man and Superman can vary greatly. Sometimes it's about a man's journey to understand or even become like Superman. Other times, it focuses on the conflicts and alliances that form between them in a fictional world.