I'm yet to hear a really good, rigorous, and reproducible definition of Creativity in the first place.
People know it when they see it, and instinctively know what it is even if they can't phrase it "rigorously".
Not all things have a "really good, rigorous, and reproducible definition" -- especially "family resemblance" notions. What is a game, for example? You can use all kinds of words and rules to describes the notion of "game" but you can always find counter-examples ( https://en.wikipedia.org/wiki/Family_resemblance ).
Maybe in the context of the HN audience (mostly people interested in writing computer programs), but for me being "creative" means being someone like Stanislaw Lem or Kafka, i.e. people who actually create new (in this case literary) worlds which are really, really interesting to navigate through, so much so that sometimes you don't want to come back into the real world.