My favourite definition is by Viola Spolin. This quote is from “Improvisation for the Theatre”, the Bible for improv comedy.
Creativity is often thought to be merely a less formal way of presenting or using the same material, in a more ingenious or inventive way perhaps - a different arrangement of the same blocks. Creativity is not just building or making something, not just variations of form.
Creativity is an attitude, a way of looking at something, a way of questioning, perhaps a way of life - it may well be found on paths we have not yet travelled. Creativity is curious, joy, and communion.