Humans fighting superhumans

The whole premise of the Suicide Squad’s formation is that nobody will miss these villains if they die. They’re expendable. Furthermore, it is also implied that they are the only ones who can go against superhuman/supernatural threats, such as Superman (if he ever decides to become a villain).

If this is the case, why are regular soldiers (such as GQ) accompanying the Suicide Squad? From what I can understand, the squad was formed for this exactly: to prevent regular soldiers from dying.

This question won’t be addressed in the future. However, speaking of regular humans, why is Harley Quinn on the team? Deadshot is the best marksman, Katana traps souls with her sword, Diablo shoots fire from his hands (and not only), and even Captain Boomerang is skilled at something. Harley is just crazy and has a bat. That’s not too much.

And this is yet again another question that won’t find an answer.