I learned a long time ago that the expression "exists as" is often a tell tale sign that others don't fully grasp what it means to say of something that it exists. For instance, to say that a unicorn exists as a concept is virtually an announcement of one's ignorance to appreciate the distinction between a unicorn and a concept. Unicorns, should they exist, would exist in the only way a unicorn could exist, as a concrete object and more specifically, a biological animal. A concept of a unicorn exists as only a concept does, a product of one's mind. Imaginary objects don't exist at all. Percepts as percepts. Pictures as pictures. People as people. Characters as characters. There's an odd saying people say: "it is what it is." A true statement, yes, but a trivial truism.
When I use the name superman I refer to something that exists.
Yes, i see, but just as lexical meaning is independent of individual usage, so too is the referent of a term independent of what you use it to refer to.
If you could accept and incorporate into your thinking that fluent speakers would ordinarily and accurately deny the existence of Superman yet understand that such fluent speakers would not therefore deny the existence of the created character we sometimes use shorthand and refer to as Superman, you might see that it's not the existence of the character that is being referred to when it's said of Superman that he doesn't exist. The referent of "Superman" without the shorthand is not a character of fiction. In fact, Superman is not a referring term at all, as it has no referent. The term 'fails to refer'. Words can have a meaning yet not have a referent, for instance, the term, "although".
But... Superman is a comic book figure. That comic book figure exist.
The comic book figure is what "superman" refers to.
Maybe you think that because that's how we talk. The author imagines a real life being that can fly, and that would be Superman, but he doesn't exist, but he wants to depict this being that could fly if he did exist in a comic book, and so he creates a character, and what exists is not the real person that could fly if he did exist but rather the character in a book. So, on the one hand, we have Superman, and on the other, we have the character. He names the character Superman, yet we're still left with the person Superman on the one hand that doesn't exist and the character Superman on the other that does exist. We shouldn't confuse what his name would be if he did exist with the name of the character that does exist.
We speak in shorthand when referring to the character and instead of saying things like the character Superman does this and that, we shorten it and day Superman does this and that, but if we drop the shorthand and speak as things really are, it's not really Superman that is a character in the comic book but rather the character of fiction named Superman depicted as doing things in the comic book.
So, it doesn't surprise me that you think what you do.