Consider for the moment the inverse proposition: Humans have no inalienable rights.
If there are no inalienable rights, then any "right" may be removed from any person at any time. "Rights" as such cease to exist, and are thus better apprehended as privileges granted or removed by some exterior agency. A person has not even the right to live and walk upon the earth if there are no inalienable rights.
If there are no rights, on what basis can there be laws? If a person has no right to life, upon what basis can we ascribe punishment to the taking of life (that taking being legally defined as murder). Without a right to life, one person taking the life of another is not comprehensible as a wrong. Laws after a fashion could be imposed by government, but such laws could not be anything but arbitrary and capricious, for without rights there is no power to bind government. Without rights, government becomes merely a rule by the strongest element of a society--and a rule constantly challenged by others.
One might perhaps argue that there need not be a society, and therefore there need not be a government, but such an argument fails to acknowledge the singular characteristic of Man--Man is a social animal. Homo sapiens sapiens, like the other great apes (chimpanzees, bonobos, gorillas, et cetera), and like a great many other animals, naturally gathers into groups. Community and society are instinctive behaviors in Man. Wherever there is Mankind, there will be society. However that society so orders itself will be the government of that society. This is no more than the consequence of Man's existence.
Man will have society--for such is his nature--and thus Man will have government--being the defined order of that society. Sustaining that defined order requires that the capabilities of man be in some respect restrained; a man may not take as he will, kill as he will, do violence as he will, without consequence, for to allow such would be to disallow the order that preserves society. Even within the social groupings of other animals, individual members of those groupings are constrained from uninhibited action; it is no different for the social groupings of Man. Thus it is that for there to be society, there must be law to bind men into society.
Because there will be society, and because society will have law, it is necessary that Men have rights--for if a man has no rights, by what power may he constrain his fellow men? If a man has no rights, by what power can he enforce the laws upon which society (that which he cannot do without) depends? A man must have at the very least the right to act to enforce the law.
Because a man must have at least that much right, it necessarily follows that, regardless of the particulars of the social order, some rights cannot be set apart from man, and are thus "inalienable".
