They are used to simplify the complexity of nature and matter by ancient people. Complete answer: The twelve elements of nature are Earth, Water, Wind, Fire, Thunder, Ice, Force, Time, Flower, Shadow, Light and Moon. Each of these elements are simplified terms for higher and complex substances.
Ayurveda believes five basic elements Pancamahabhutas (space,air,fire,water and earth) manifest in the human body as three basic humours known as tridosas(Vata,Pitta and Kapha). These three govern creation,maintenance and destruction of bodily tissues as well as the assimilation and elimination.