Man has rights because they are natural rights.

“Man has rights because they are natural rights. They are grounded in the nature of man: the individual's capacity for conscious choice, the necessity for him to use his mind and energy to adopt goals and values, to find out about the world, to pursue his ends in order to survive and prosper, his capacity and need to communicate and interact with other human beings and to participate in the division of labor.”
― Murray N. Rothbard