In the Declaration of Independence, Thomas Jefferson's assertion that "all men are created equal" primarily reflects the principle of equality before the law. This phrase encapsulates the Enlightenment idea that every individual possesses the same inherent rights and should be treated equally by the legal system. Jefferson was advocating for the idea that regardless of social status, class, or other differences, all individuals should have the same legal rights and protections.
While Jefferson's statement has been applied in broader contexts, such as the fight against slavery and for civil rights, at its core in the Declaration, it speaks to the legal equality that was foundational to the emerging American democratic society. It does not, however, imply equality in intelligence or an expectation of social equality, which are more complex and nuanced concepts that have evolved in the context of civil rights over time.