What is an important part of the cycle that has made and kept the earth a place where living things can survive?

The answer is "Erosion".

Erosion is a cycle where natural powers like water, wind, ice, and gravity wear away soil and rocks etc. It is a geographical procedure, and part of the stone cycle. Erosion happens at the Earth's surface, and has no impact on the Earth's mantle and center. The greater part of the vitality that gets Erosion going is given by the Sun.