The purpose of creation stories can vary based on cultural context, but a common purpose is to illustrate how the earth came to be. This response aligns closely with the fundamental objective of many creation myths, which is to explain the origins of the world, humanity, and the universe. However, creation stories can also serve other purposes, such as teaching lessons or preserving cultural traditions.
In a broader context, responses like "to teach a lesson that would help people survive" and "to tell stories about ancestors" can also be valid, but the most direct answer to the question regarding the purpose of creation stories is primarily focused on illustrating the origin of the world.