You have missed the essential argument: The claim is that "someone ELSE's life begins at conception". Obviously all cells are alive, but they are your own until

You have missed the essential argument: The claim is that "someone ELSE's life begins at conception". Obviously all cells are alive, but they are your own until they become a new human being. Once that new human being is created, it's no longer your decision to make. At least, that's the moral argument being proposed.