I've come to realise that trying to say what creativity 'is' might be quite a futile goal in itself. There are just so many different ways of understanding what it might be, and a whole list of frameworks from which it may be defined.
It is much like language in this regard - meanings shift and change. More than that, however, it is a concept which breaks out from the words which attempt to define it. Everyone has a sense of what creativity is, even if they cannot put it into precise words. It is evocative and emotional, in the same way that a particular word might have a sense of power behind it.
I know that mayn't make much sense. I might revisit this later and try and express this ill-defined thought a little better!