Which term best describes a process that supports human life and economies at no cost to humans?

Symbiosis

The term that best describes a process that supports human life and economies at no cost to humans is "ecosystem services." Ecosystem services are the benefits that humans receive from ecosystems, such as clean air and water, climate regulation, pollination, soil fertility, and recreational opportunities, among others. These services are essential for supporting and maintaining human well-being and economic activities, and they are typically provided by natural ecosystems free of charge to humans.