Every atrocity carried out by human governments has been enabled by the person or group with the biggest weapons – or the most votes – first declaring that some classification of humans is not human-enough, and has “never had rights.”
(For instance, the monarchists’ determination that the people have no right to self governance which is not allowed by the king. Or the Dred Scot decision by the US Supreme Court, in which Taney declared that the founding fathers never meant for former slaves to become citizens. Or the fact that women have never had and do not currently have their rights protected in certain Islamic nations.)
The only reason to allow abortion is discrimination based on abilities, characteristics, or something besides the humanity of the human involved. Whether recognized in formal law or not, the right to life precedes all others and is inalienable from creation.
Again, whose life is being ended and why? Life, liberty and the pursuit of happiness are inalienable, from creation. The hierarchy is intentional and purposeful: if the right to life denied by killing, then no other right has meaning beyond that allowed by the person or group with the biggest weapons.