So what are the truths that Jefferson asserted?
“We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.”
Jefferson asserts three self-evident truths: that men are created equal, that they possess rights given to them by God that cannot be taken way, and that these rights include the right to life, liberty, and the pursuit of happiness. These truths do not stand alone. Through his structure and punctuation, Jefferson connected them with each other and separated them from a second set of self-evident truths. To understand his meaning (as best we can), the reader must interpret them within that context.
So what did he mean when he claimed all men are created equal? In the context of the chain of propositions in the argument as it unfolds, Jefferson seems to have meant that God created men equal in their common humanity and human nature. No one is created to rule over others or to be ruled over. There is no room for a hereditary aristocracy. This is what his original draft suggests, where he wrote that “all men are created equal and independent."
A comment he wrote in a private letter shortly before his death sheds additional light. In this letter he paraphrased Algernon Sidney:
"The general spread of the light of science has already laid open to every view the palpable truth, that the mass of mankind has not been born with saddles on their backs, nor a favored few booted and spurred, ready to ride them legitimately, by the grace of God."
(As a side note, the idea of creation, of course, is not all that self-evident. If Jefferson had written the proposition as "all men are by nature equal," the proposition might be more self-evident.)
This concepts of equality entails the next self-evident truth: that men possess God given rights that cannot be taken away. Because men are created or by nature equal, they possess equal rights. (Again, rights as gift from God is not self-evident. Because Jefferson was not a Christian, he did not find these rights in the Bible or in any creedal statements. I doubt any Christian can). He derived them from human nature. This can be seen in his original draft, in which he wrote that "from their equal creation they derive rights inherent and inalienable." The most general or fundamental rights include the rights to life, liberty, and the pursuit of happiness. Every man has the right to defend and protect his life. Every man has the right to exercise natural or personal liberty in fulfilling his potentiality through rational choices. And every man has the right the pursuit happiness through those rational choices.
Two caveats, however, must be added. First, the idea of happiness is an ancient term with a long history of meaning that differs from how it is conceived today. We think of happiness as the pleasurable psychological state that results from acquiring whatever it is we want. The traditional meaning, going back to Aristotle, was "thriving" or "flourishing." It meant fulfilling one's specific human nature. In other words, pursuit of happiness implied seeking those things that help one thrive and succeed at being human. Second, natural rights claims are reciprocal. Because of common human nature, every man's rights claims must be respected by every other man.
Sometimes men do not respect the rights claims of others. That leads to the next self evident truths of Jefferson regarding the purposes of government.