There is a concept of non violence from India called Ahmisa, which is present in multiple belief systems. The Jain religion considers all eating as an act of destruction, which clearly posses a problem as they include plants as living creatures.
Buddhist thought avoids this dilemma by simply defining plants as not being alive, more akin to crystals and so forth.
Most people think that we have different moral duties to living things vs non-living, yet how things are defined in our imagination, has real world effects, in my opinion.
I have in multiple points in this and related threads pointed out that some of the utility I find in fantasy is precisely asking questions about the complex problem of the moral duties one living thing might have to other living things, based on different natures of living things might have. As your brief survey indicates, this problem is difficult enough that lots of different highly intelligent and rational people have come to slightly different conclusions. I don't have any desire to argue or pass judgement on any of the above claims.
I merely ask that you stop passing judgment on my own exploration of these topics. I'd equally ask you to not assume that if I'm exploring topics like, "If brocolli was sentient, would it be OK to eat it?", that you not assume that the motive of that exploration is racism, any more than it (necessarily) was the motive of the Jains, Buddhist, and so forth you mention above.
But examining the issue, especially given the origins of the genre, and asking ourselves tough questions, is important, I think. The casual, narrational racism of the Solomon Kane stories certainly is leading me to ask these questions.
And that's exactly what I'm doing, thinking about tough questions. I feel like I tried to raise a bunch of tough questions in this thread.
But you know what question for me isn't a tough question: man's duty to his fellow man. I have I think a perfectly satisfactory answer to that one. The nature of racism is not one that provokes in me any real intellectual curiosity. I'm perfectly satisfied that I know it is wrong, that I know why it is wrong, and that I know what an effectual cure would look like. It's actually probably the easiest of questions in the complex universe of questions about moral duties between living things. And racism is itself only one species of hatred, in the overall universe of justifications man has for not treating other persons the way they would like to be treated. I don't really have any interest in discussing these things as a point of debate, because either you already get them in which case what's the point, or you are going to bore me with your theories justifying your hatred, scorn, and mistreatment of one group or the other. My impression is that a lot of the people expressing the most concern about this sort of thing, are the ones most struggling with their own mental models of how other people deserve to be treated. Nobody enjoys talking about racism as much as a racist, and the things that change over time are simply which group of racists are tolerated in public discourse.
I don't need bullywogs, goblins, gnolls, kobolds, aarokroka, dragons, vampires and all the rest to model mankind. I can just use humans in all their wonderful yet limited diversity. I don't need any symbols for any real world racial groups. When someone comes in and starts trying to map aarokocra and bullywogs to some real world racial group, I'm appalled. I'd ask you to stop trying to find race within my aarokocra, bullywogs, and orcs. The obsession is bizarre.
I've never read the Solomon Kane stories. I have read about half of the Conan stories. I would not use them as a guide to answer the question how one ought to treat ones fellow man, regardless of their skin color. Howard is a complex man with a hard life and many difficulties he was struggling with, and his thoughts evolved over the course of his life. As I would summarize his thoughts on race, his own thoughts seem to be quite congruent with one of those now popular racist authors, such as Jared Diamond of "Guns, Germs, and Steel" fame, who people aren't ashamed to quote approvingly since he's given Howard's views a little twist and new language. But again, I don't really have an interest in arguing over what author's views are so racist one should not read their works. I notice that for all your condemnation of the works of Howard, you are reading 'Solomon Kane' and it's provoking you to ask "hard questions". Well, good. Let's be careful then about who we censure. Even libertarians.