What kind of rules did Islam establish for the preservation of life?
Islam Religion attaches great importance to life. It regards slaying as one of the great sins and again regards killing a human as the greatest crime as killing all humankind. He who kills a soul unless it be (in legal punishment) for murder or for causing disorder and corruption on the earth will be as if he had killed all humankind; and he who saves a life will be as if he had saved the lives of all humankind. (Al-Maidah Surah, 5:32)
According to Islam, The life and blood of an innocent cannot be wasted even if it is for the benefit of the humankind. Both are equal in the sight of Justice as they are equal in the sight of (His) Power. That is to say, as there is no difference between for Gods Power to create a human or humankind, at a glance of His infinite justice a humans right is as important as all of the humans rights; there is no difference between them.
The Holy Quran, as it pronounces death penalty for the ones who commit murder in this world, it condemns them to the torture of the Hell fire in the Hereafter. Surely, it is also God Who gives life and causes to die.
Humans blood and life is so important in the sight of Allah (swt). In fact, blood feuds are going to be the first trials in the Hereafter. Humanity is the provision of the preservation of life but not being Muslim.
It is prohibited not only killing humans, it is also prohibited killing harmless animals; even animal life is protected in Islam, because Islam is predicated on mercy and justice.