I'm not saying this is what James Gunn meant to say, but to me Lois Lane for much of the movie — especially when she interviews superman — represents the people who are genuinely good but have been jaded by the world and bought into what everyone in power has told them about things being "too complicated" for them to do what's right. So much so that she sees people like Clark, who stands up and says "no, we can actually do the right thing", as doing more harm than good when in fact he is only doing harm to the power-hungry leaders that have caused the people like Lois to believe that in the first place.
This is the kind of radical hope and radical good that I see Superman as teaching us; that we don't have to play along and pretend that we don't know what's actually going on when imperialistic countries try to do genocide while claiming theyre "helping" those they're killing. We don't have to accept the line that "it's too complicated" to do good and make the world better. We can regard that claim for what it is: upholding the status quo that's actively making the world worse. We can actually just do the right thing.
It is not naive to do good and encourage everyone to do the same.