Words change over time but I don't know if that means we should get philosophical about it. The reality is slavery grew and developed along with agriculture and some of the earliest fields we were worked by people forced to work them. Conquering your neighbor and enslaving him and his children was once thought to be a good and noble thing to do and people who excelled at it were held in high regard.

Julius Cesar was loved by his people in part because of all the wealth he brought by capturing and enslaving people. The Roman Empire had an economy based almost solely on slavery as did most of the world. The idea that it is bad to force others to work for is a new idea but you should be happy that it has become so widespread that words we used to use to describe those people have taken on new meaning. It isn't bad that a word that used to mean farmworker now means something bad it is good that we don't need a name for a person who wants to work a different field.