The expulsion from humanity is part of many rights violations because these violations can only be justified when the other is labelled as something less than human. Human rights can only be violated when the victim is not really human. Only a non-human does not have human rights.
If a person has rights because of his or her humanity, then it is important to recognize the right to belong to humanity. This right is indirectly expressed in art. 6 of the UDHR:
“Everyone has the right to recognition everywhere as a person before the law”.
Every culture has, at some moment in time, excluded certain classes of humans from humanity. Some cultures still do. Some of the major religions have considered or still consider non-believers to be an inferior species, outside of humanity, not real humans and therefore not entitled to the same rights.