If you want to know why we have morality then you could either argue that it was given to us by an intelligent designer (a deistic one) or that humans ancestors worked better together in groups and a stable group could not form without a sense of morality and so ones with morality where able to band together with others and survive more so they could spread their genes more leaving more ones with morality m among mor groups could form, and thus through evolution the species developed a sense of morality which carried on through the gene pool all the way to modern apes including humans I won’t tell you which one is true but those are the possibility