‘Human’ is a scientific term. It means of or produced by a member of the species Homo sapiens and/or closely related species.
"Person’ is a socially-defined concept. We members of society get to define what a person is.
‘Human’ is generally an adjective: ‘human being’; ‘human tissue’; ‘human artefact’; ‘human corpse’,. As a noun it overlaps in meaning with ‘person’.
‘Person’ generally means someone recognises by society as a member of society. This recognition varies from society to society.
Pro-lifers generally recognise any group of living human cells with the possibility, or previous possibility, of developing or continuing as a human child or adult as a person. Therefore they seek to provide the protections accorded people to zygotes and to human bodies that have no higher brain function.
Pro-choicers generally see personhood as applying to born human beings or those with the potential to be born and continue developing. Some believe severe abnormality, especially that leading to inevitable death means that a fetus can be considered not a person, in that they will never be a functioning part of society. But in some cases they recognise these beings as people but agree it is moral to kill them as the lesser of two evils.
Shouting ‘HUMAN!’ and 'NOT A PERSON!" at each other, or even doing so politely does not advance the argument.
The question is, can we find ways of accomodating these two views in a democratic society without using the power of the state to enforce our views.
In my view we can: we can agree that choice is maximised when people do not become pregnant when they do not want to be and that people who do want to be pregnant deserve the support of the whole of society before and after conception and birth.
And we can discuss and advocate our philosophical positions and persuade people to our points of view without using the state to control others.
And yes, I know that if there we a large group of people who considered those with red hair not to be persons we would have a problem. But there isn’t, and we don’t. We do have a problem in living together in a democracy.