smerel
The authors aren’t unknown. You may not have heard of them but many authors of Golem stories are known. Wikipeida provides a list Berthold Auerbach, Gustav Philippson, Franz Klutschak, Adam Tendlau , Leopold Weisel
Much like most people can’t name the author of Peter Pan
There are lots of made up stories that achieve fame. Far more than the Golem.
You are right perhaps those arent the best comparisons a better comparison would be Vampires who invented it ? nobody knows yet it is something most people have heard of (far more than the Golem) Does that lead credence to their existence? OF course not