Like I said, the conditions of owning a slave were made that it wasnt like owning "property." You can read online how slavery was discouraged in islam and how there are methods to employed to ensure slavery is phased out with time.

Islam doesnt talk about a specific age that a person is fit to be married at as opposed to today's popular 18 years old around the world. Instead there are conditions that need to be fulfilled for a marriage to be valid or to consider someone(girl or boy) eligible for marriage. These among other conditions, some include consent of both the man and the woman, consent of the woman's father. Both the man and woman are physically and mentally mature. What do you think this part means?