@logic

1. Person in coma is still a live sentient being.
2. Agreed (although the jury seems to still be out in regards to insect sentience. Looking forward to that one being settled better).
3. A fetus definitely is an animal although its sentience is debatable because our ability to remember and express past experiences is practically nonexistent until we get to be around two years old so there's no way to verify this yet). The past health and awareness of the person in the coma isn't relevant to its present state. Something is no less dead just because it used to be alive.
4. The meaning of the word is what this is all about. My initial point was merely that sperm aren't humans but fetuses are. No need to fear dictionaries. They can help us to avoid all kinds of misunderstandings. I see no contradiction but, by all means, explain if you disagree. All this is about is properly understanding objective reality and discussing it accurately. I made no moral judgments or anything else to support your notion that I'm arguing from an emotional position that's rooted in some sense of identity or whatever else. As a side note, one might suggest that your perceived a moral judgement where there was none because of your own hypersensitivity, which could be rooted in guilt or a fear of your own identity's framework being challenged... but I guess that would getting into a whole other topic.
   Of course, the older a person is, the more physically developed it is (until the brain is finished forming in our early twenties). You just said that a fetus doesn't "resemble" a newborn, which is an observation about its appearances. My point was that such a differentiation is irrelevant to the question of whether or not its human, which was the question at hand.
   Calling something illogical, mindless, or simplistic doesn't make it so and has no place in any serious debate.
5. If you want to tackle moral questions about killing others, we can certainly do that too... although this discussion hasn't been about that thus far so it would mean venturing into a whole other subject.