Social progress as the gradual extension of human rights
The progress of civilization - of (negative) rights, can largely be framed as the extension of personhood to every human being. Sometimes this process can take centuries or even millennia to reach certain groups.
To put things in a slightly more rigorous way, the right I am talking about here is the right not to be aggressed against, not the "right" to healthcare, or some other nonsense expropriation couched in vague terms. We're talking about consistently applying the NAP (Non-Aggression Principle) to every human being on earth. Boy, are we far away from that.
One of the key issues is that the existence of the State makes nobody safe. Government agents can, at will, initiate aggression against peaceful adults engaging in voluntary, mutually consensual interactions. Even when people within a particular group are generally seen as full human beings, they are still subject to arbitrary rights violations in the form of taxation (theft), imprisonment (kidnapping), conscription (enslavement), war (murder), etc.
Up until a couple of centuries ago, the institution of slavery ensured that millions of people lived and died without having basic human rights. On a fundamental level, their right to own themselves, and to decide what they do with their life, was not respected. If they were murdered, their murder was not treated as seriously as the murder of a "free man".
In many societies even "free men" did not really have rights. Only a certain class, sometimes closely connected to the ruling class, was allowed to own property. However, even the rights of people within that group were sometimes unstable, since these societies were largely built upon the principle of "might makes right", and as soon as someone's political and economic power waned, so too could their "freedoms".
Modern western societies have in many ways improved things in this criteria, but in many other ways slipped behind. While slavery has been abolished, women are now regarded as highly before the law as men (perhaps more highly, even), and non-whites now have the same rights as whites; a group that was always accepted in classical western civilizations such as Ancient Greece and Rome, homosexuals, are in our "modern" societies having to fight for certain rights without which they are essentially being treated as second-class humans. For instance, in many jurisdictions if two homosexual adults consensually marry, they open themselves up to State aggression.
Sometimes the existence of rights is conditional not upon a certain class assigned at birth, or a sexual preference, but upon a profession. Thus prostitutes, adult women who have consensual sex with adult men for money, are both in the law and in the media and popular imagination, treated as sub-human.
Another category is the case of the drug user. In almost every western country today, someone who chooses to smoke marijuana opens him or herself up to assault and kidnapping at the hands of the government.
Note that in the above two examples, both the prostitute and the drug user do not have the fundamental right to self-ownership. Their right to do with their body as they please is not respected. Does that remind you of the description used above in the case of the slave? It should.
Moreover, as any individual may at any time choose to prostitute themselves or consume drugs, everybody is subject to the same "contingent" rights. "Sure, you have rights" says the government "as long as you follow my arbitrary and morally vacuous rules. Stray from them, however, and you will be treated as property." As you can see, our society has a long way to go still.
But perhaps the largest group of people not seen as human beings, and this it would seem regardless of any other distinguishing characteristic, are children. For the first 18 years (more or less depending on the government), children do not have fundamental, basic rights. They do not have the right to leave their parents' custody, even if their parents are coercive and harmful. Even obvious abuses such as spankings are tolerated by many societies. Not just tolerated, but widespread. The vast majority of women in the UK spank their children, for instance.
If you follow the link above, you will discover that child abuse is probably the greatest determining factor for domestic abuse, violence on the streets, susceptibility to drug abuse, alcoholism, smoking, suicide, depression, anxiety, over-medication, etc., etc.,
And the fundamental cause is that children are not treated as human beings. In some sense of course they're really not full human beings until a certain age. Their brains are not fully developed, they are less able to provide for themselves and are dependent on their parents, and their small size makes it harder for them to protect themselves from aggressors.
But it is precisely these weaknesses that place a moral obligation upon their parents (who as their guardians voluntarily took it upon themselves to have children), to treat them with even greater respect, kindness, caring, and empathy than any full-grown adult.
A full-grown adult can leave their abusive partner, and has legal recourse. A wife can divorce a husband who beats her. She can sue him. She has basic human rights. Children, on a fundamental level, do not. Child abuse should rightly be seen as the most inhumane and life-destroying activity possible for humans to engage in.
Yet the vast majority of people in our society view children not with a greater moral standing than adults, but with a lesser one. They take their weakness not as a call to greater care and kindness, but as an opportunity to raise obedient little drones who their parents will treat as property (slaves) until they reach the age of human rights - 18 years old.
If libertarians want to enact lasting change in society, we should also look at the root causes of slavish obedience, lack of critical thinking skills, a propensity to violence and war, etc., and not focus on merely trying to extinguish the symptoms found in government policy.