Humans and other social animals work very hard to eradicate pain because pain is next to death on the spectrum of things to try to avoid. There is a problem, however, in that humans have been inventing tools, weapons and machines that are designed to inflict pain and death in order to conquer and use other humans for thousands of years. Somebody want to continue this thought? I don't know exactly where to go with it. .christine3
Inflicting pain and death is part of survival for predators and frequently pain and risk of death are part of predation. And humans are certainly predators. Avoiding pain and death is a characteristic more of prey than predators, and social prey animals develop moral strategies to minimize pain and death for the social unit. One universal moral imperative is protect the next generation at any cost. Although it might be argued that this is a species survival instinct rather than a moral precept for our purposes the difference is probably insignificant.
The real problem for humans is that they are both prey and predators. In tribal societies (aren't we all) especially nomadic tribes resources are generally controlled by other humans and tribal survival means better killing tools, weapons and machines and not incidentally tribal moral imperatives that encourage their use. Kill or subdue all the heathen, gentiles, or other "non-humans" that is, not us, with the fear of pain and death. It is no accident that religious morals distinguish strongly between "us" and "them" and discourage any sympathy or empathy for them.
It is perhaps significant that the "thems" have not only developed highly efficient defensive killing and pain inflicting weapons, but have also developed more inclusive moral imperatives that recognize others as important as well. Probably the most radical and important moral innovation of the Enlightenment was that all are equal. OK all men, but that was the critical break with the "Us v. Them" morality. And put the human race on the slippery slope to the humane treatment of all. There are still those trying to claw their way back up the slope to the rock of hatred, frequently led by God the rock, but those "defensive" horror weapons in the hands of the relatively enlightened are formidable intimidators of the remaining predator humans.
Interestingly one of the most intimidating of those weapons is the Enlightenment idea that all are equal. The people in the streets have no fear of pain or death, and can in fact defy the most powerful offensive weapons. See Tiananman Square or Kent State University. Certainly many were hurt and killed, but the mores of the world were radically changed.
Incidentally, I would put pain as a much greater fear than death. Suicide is a common solution to pain, emotional and physical. Three banksters seem to have heard the call to jail them and fear the pain that will be inflicted if those calls are implemented.