...right after sext. (And to think the monks have been sexting all these centuries.)
John Locke, particularly in his Second Treatise, elaborates a system of rights that are essentially natural rights, even though he does make a bow to God as the original bestower of life and the earth to humanity. Tom Paine then wrote his Rights of Man, further developing the idea of natural right, and in his case, not with reference to divine donation (Paine was notably anti-religion; he was marginally Deist). There is plenty of philosophical basis for a well-developed conceptual system of inalienable human rights, though, of course, there would inevitably be disagreement as to exactly what they are. In fact, I think that has something to do with some political debates we are having in this country.