A human and a human being are synonyms.<quoted text>
They CAN be used interchangeably, when both apply. It's not required that they are. For example, YOU are both a human and a human being (albeit not a very good example of one). A fetus being gestated inside a human being is a human, but not a human being.
You can say so all you like, but I don't have to debate as though it's true.
You're making up a subjective & random vocabulary rule in order to excuse executing little humans.