First off, I am also pro-choice.

I disagree, however, with your position because it implies that things like a person's humanity is (or ever can be) regulated by the Constitution or any other legal document.

I guess I have two questions; Do people's rights exclusively come from whatever the State allows them to have? And as long as something is legal, is it automatically morally permissible?

I ask because it seems that your argument is that, as long as the State doesn't recognize someone as a person deserving rights, then they aren't. This of course leads to a lot of uncomfortable implications: Were Blacks truly only 3/5s of a person until the State decided otherwise? Did women not have an inherent right to vote and run for office until the State decided they did?

Leaving it up to the State to pick-and-choose people's human rights is a very slippery slope.

Also, how do you explain the fact that non-natural born individuals are granted rights under the Constitution? If it all comes down to if an individual is a citizen, then why do they deserve rights?

Not to mention that you exclude the portion of the 14th amendment which states "Nor shall any state deprive any person of life, liberty or property, without due process of law..." So even in the amendment you cite, it still comes down to a debate of personhood, not citizenship.