Welcome aboard, Dr. Robb. There's no need to be defensive about the artificial origins of Esperanto. So what if one person essentially made up from whole cloth the grammar, syntax, spelling, etc.? That certainly doesn't make it a useless construct. That it has evolved (and is evolving yet) only underscores its different origin from other languages - in 300 years, "original" Esperanto will be unintelligible to Esperanto speakers.
On the other hand, to say that all languages were "created" by humans in the same way Esperanto was is patently specious. All of our many languages evolved from preexisting forms through the contributions of millions of people using the language(s) to suit their needs. As will happen to Esperanto. But no committee of Cro-Magnons decided the entire structure of their language at a sitting and presented it to the grunting populations outside their cave. The ability to speak and the vehicle of language evolved initially from lesser skills. The origins of Esperanto and virtually every other language that has ever been are inarguably different. Again - So what? That doesn't make Esperanto bad, but it does make it unique.