Why do you think these cells are important for various body functions?

Because they make up the body and have various purposes

Different types of cells play different roles in the various body functions. For example, only sperm cells and egg cells are capable of producing offspring. The body also has specialized cells that produce specific substances the body needs, such as hormones.

you did not attach the discourse, but i assume it to be the discourse on the origin and basis of inequality among men (the original titile in french is: "discours sur l'origine et les fondements de l'inégalité parmi les hommes"), also know as "second discourse". in this discourse, jean-jacques rousseau emphasizes that private property is the basis of all inequalities.

therefore, what enabled the old regime to maintain as long as it did was private property.