Okay. 1st off, since super heroes aren't real the debate is endless.. It will never, ever end. It's all subject to interpretation.
People interpret it different ways. Your son is in the camp (along with most comic fans) that believes that a "superhero" is anyone who "saves the day" by performing superhuman feats, through biological, artificial, or magical endowment, that no ordinary mortal man would be able to achieve alone or with non "super" resources. This would include Ant-Man and Iron man in the superhero category.
You are in the camp that seems to think that a "superhero" and a "superhuman" is the same thing. Your son however would argue that although a superhero CAN have all-natural super powers, that is not the only qualification. He's saying that as long as you can do "super" things you can be considered a superhero regardless of where your special abilities are coming from.
Also there's kind of an unwritten philosophy when it comes to this topic among comic readers and that's, "Yeah, anyone could roll out of bed and pick up Green Lantern's ring and have super powers. But would you actually use these powers to successfully thwart diabolical plots? Could you actually even control that power? Do you have the will to make all the sacrifices that being a superhero comes with while staying disciplined, selfless and uncorrupted? If not, then you aren't Green Lantern, you're just a dude who has his ring"
And that's what would upgrade a person from "guy in a suit with powers" to "superhero" in their eyes. It's not just the power, its also the willingness to be able to do superheroic stuff your entire life as well. If you had Superman's powers but you spent your whole life doing private accounting and nothing else, you're not a superhero. You're just a very strong accountant.
