I agree with most of your arguments, so I don't really have the stomach for pointing out their weaknesses. But these are arguments based on science, they are not scientific facts themselves. The Naturalistic fallacy, for example, has never been proven to be fallacious in the laboratory. I can't even imagine what such a proof would look like. It's a philosophical concept, discovered by philosophers, and there is no consensus as to what it means to commit that fallacy. You are partially acknowledging this when you refer to these claims as "widely believed principles". I agree with you that the embryo is not an individual, but that is also a philosophical claim, (called an ontology) not a scientific fact. Those kinds of principles make science possbile, which is why science can't prove or disprove them. Read some of the other essays in the series, and you might get a better understanding of the distinction I am making here.