There is no further deconstruction necessary of living human being than there is of living human person. Either the zygote is not alive, not human, or doesn't exist. That's the scope of the rebuttal.
We agree that a zygote is alive. So the question is, is it a human person? And you answer depends upon how you define "human person". If you define it by DNA, then your answer will be yes. If you define it by brainwave activity, then your answer will be no. You cannot avoid the necessity of defining your terms.