Pain, Self-Sacrifice, and a strong sense of Duty have been key underpinnings of the concept of the Super-hero since well before Marvel Comics arrived and indeed before DC Comics arrived...
...Supergirl, a product of the Atomic age and the fear of the apocalyptic power of the nuclear age. One of the last of her kind and believed the only survivor of a doomed city which escaped Krypton's end Kara Zor-el was quite the opposite of her cousin Kal-el, unlike him she was old enough to witness the end days of Krypton and her struggling but doomed home on Argo City, a fact rarely touched on at the time...
DC Comics, under an earlier name, was the first source of super-hero stories, being the publisher of Superman, the character who started the whole genre.
Also, Supergirl has had two somewhat different origins which you're blending into one.
The first had her born to the Kryptonian survivors of Argo City (which outlived Krypton, surrounded by a dome which served as a spaceship hull), maybe over a decade after the planet's destruction, never having seen Krypton itself. (The dome was punctured by meteors during her teens, leading to her being sent to Earth.)
Her post-Crisis (post-InfiniteCrisis?) origin saw her alive as a teen on Krypton and launched into space at pretty much the same time as Kal-El, taking longer than him to land on Earth, still a teen when arriving due to suspended animation. In this version, Argo City didn't survive Krypton's destruction for any real length of time, nor did she live there after Krypton's destruction. (In the nu52 version, Argo was destroyed at the same time Krypton was, with her barely getting away in time thanks to a time-traveling Kon-El.)
We want accuracy when addressing the histories of these characters. Factual errors can lower the value of a well-written piece.
Isn't her father now the current Cyborg Superman?