What demonstrate the creativity of the mayan people

Do you mean you're looking for an example of something creative that the Mayas created that can be used now to demonstrate that they were creative? ( I don't know whether in the past the Mayas had to prove their creativity...)

A good example is the Maya script: the only script that can fully encode a language that we know of from the Old World. The Maya script, is also especially ornamental, and served also a decorative purpose; this is definitely a good example for Mayan creativity.