No, not correct. The status of human being is not a Constitutional concept, it is a biological concept.
One concept does not exclude the other.
Now if you want to discuss citizenship designation as per the Constitution, I'll defer to your expertise regarding the Constitution. Personhood is a completely different concept that overlaps both the designation as human being and citizenship.
So you believe/claim. Your belief does not authorize our government to violate a pregnant womans right to equal prtotection under law.
We all know you are firmly 'pro-choice'. The issue being discussed has moved to 'constitutionally define embryo' ... as per your desire to use some Constitutional argument to now disenfranchise the embryonic age of the human being. The status as 'human being' is not a constitutionally confined question ... there must be a component of moral principle in order to discuss the status of the human embryo. Citizenship is definitely a constitutional question. Personhood is not and status as a human being is definitely beyond even penumbral vagaries.
When you assert, "At some point an embryo/fetus becomes a functional person, "viable", -- with equal rights to its mother." Define 'functional person', to remove any ambiquity please. Science has shown that the unborn are capable of many of the 'functions' of born individuals, even well before 'viability'.