Well that would seem to make the rights in question not particularly inalienable. In fact if we're talking about the US slavery _is_ legal in certain contexts. So it's definitely not inalienable. Only in the context of voluntary agreements between private citizens.
This has nothing to do with the founding fathers. The Ancient Greeks talked about natural law. The UN passed the Universal Declaration of Human Rights. 193 countries have ratified at least parts of it.
Again, I beg you to at least read a paragraph or two off Wikipedia.
Well I wouldn't call it a strong argument...
Nonetheless the goalposts were never shifted. The question was always 'should'. So I'm very confused by your confusion.