Superman loved humanity. That was a Fact. But Superman was little more than a mask and Clark's feelings are more complicated than that. Clark doesn't love them, not always, but he does believe in them. Clark has faith in humanity, like some people have in religion. There is such good in people, so much that it hurts to look at them sometimes because he can almost see it in them, like a golden aura. And they have so much potential. Any and every one of them could be great and Clark doesn't think they know how inadequate they can make him feel. Clark died defeating Doomsday, but he did so knowing he had saved humanity from that monster. And that was the happiest moment of Clark's life.
But monsters from outer space rarely attack Earth and tsunamis don't happen every day. Most days he's saving the humans from each other.
People think that Lex Luthor is Superman's arch-nemesis and they're right, mostly. But Clark has a certain amount of respect for the man. He's so evil it makes Clark feel physically ill at times, but he has taken hold of his greatness and mastered it. Clark has to respect that.
Then there are the days where there is no supernatural disaster, no acts of god or immoral billionaires. And these are the worst days. These are the days he has to face the common criminals. The muggers, the thieves, and the arsonists. The kidnappers, the murderers, and the rapists. This is the humanity that Superman – that Clark – is supposed to love. The punk kids that'd rather join a gang and kill each other than go to school. The man that burnt down a building full of people for the insurance money.
The mother who had beat her child while her husband watched on without comment or protest. Clark had tried to rush the boy to the hospital, and he had died in Clark's arms.
Some days Clark just wants to tear the costume off and stop. Stand back and let them destroy each other.
These people do not want to be saved.
These people do not deserve to be saved.
But these people need to be saved.
So he'll slap on a fake smile and a love for even the meanest of humans and go on saving them. Because Clark has faith that, one day, they'll learn to save themselves.