Which is why we need the Amendment to protect the existence of those who aren't born yet. There is currently nothing in the Constitution that gives any protection to the unborn.
Your heart may be in the right place, but your head is out to lunch on trying to redefine "person".
You can only say that if you do what Blackmun did: refuse to recognize the personhood of the child in the womb.
Conversely, if you admit the obvious, that the child in the womb is a human person, the Constitution's clear words protect them. Even Blackmun admitted this.