Yeah but how does he go undefeated for years on end, lose once and for the first time, and then just fall apart and continue to lose for the majority of the rest of the movie. Superman is the apex superhero, he is above all. Outside of some insane Marvel celestials, he would smash the entire Marvel and DC roster, certainly true of any Marvel character on film. But now he gets beat up. Even a clone would be a lesser being and unable to handle the one who is the source of the power they share.
The idea is he could destroy everything. The entire planet if he wants to. He choses not to. He is good and restrains himself for the sake of the planet that welcomed him.