A) I’ve never been swayed by the argument that I might not be here given my mom having an abortion. I honestly don’t care it makes zero difference to me. I would never know that I missed out on anything. It would be as if I were a tapeworm. Killed by Ivermectin.
I never made that argument.
B) The lifeform after conception has the propensity to be human. But it is not human anymore than a dog is human until it shows the characteristics that make humans human. Not a specific DNA chain mind you, because, after all we share many parts of our DNA with other life forms. A larvae is not a butterfly no matter how much you want to classify it as a butterfly.
If Neanderthals had survived alongside us with extremely similar but slightly varied DNA would their lives be worth more or less simply because of that variation?
False. It is human. It is not and cannot be anything else, regardless of it’s capabilities or lack thereof. And if you’re making the argument that human life is only valuable based on what it can do (I’m assuming you mean reason, communicate, have conscious awareness, feel pain, etc.), I would encourage you to think that through to its logical and moral conclusion. It gets you to some ugly places.
And sharing common genetic building blocks as other species is irrelevant.
And the larvae/butterfly analogy actually proves my point. Let’s assume we’re talking about a monarch butterfly. That individual organism is a full member of the Danaus plexippus species the entire way through its life cycle. Saying a larvae is not a butterfly is equivalent to saying that a teenager is not a senior citizen. Those are both true statements, but they don’t prove the point you are trying to make. They actually undermine it.
So while a zygote is not an embryo is not a fetus is not an infant is not a teenager is not a senior citizen, the organism at all of those stages is 100% Homo sapiens or “human” if you prefer.
And as far as Neanderthals, if they survived to now, I believe their lives would be just as valuable as a Homo sapiens’, and valuable at every stage of development too. Many (maybe all?) modern humans have trace amounts of Neaderthal DNA due to intergroup breeding.