Thomas Jefferson carefully drafted every word of the Declaration of Independence. In it he recognized that our unalienable rights are endowed by the Creator. He said, "...to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed."
Jefferson, having accepted the Enlightenment discoveries of Locke and Rousseau, believed that human beings in a state of nature were ruled only by the Law of Nature established by the Creator - and also that the Creator's Law of Nature dictated that no human be ruled by another. It is from there that our Founding Fathers identified the Creator-endowed rights, particularly life, liberty, and the pursuit of happiness.
Thus Jefferson clearly gives only one purpose for the institution of Governments: to secure each individual's Creator-endowed rights.