Legal Personality and Natural Persons
Therefore from a legal point of view there a person is anything that the laws of a particular country recognize as having a bundle of obligations and legal rights. Hence persons in this legal sense are of two types as namely are - legal persons and natural persons, and they are said to possess as "legal personality".
Therefore natural persons or human beings now have the legal personality under the laws of probably all the nations of world. Conversely this was not so during within the days of slave trade. So hence a slave, though a human being that had no obligations or legal rights under the laws of those countries, that recognized slavery.