[lucksack]

My point in OP was that if one thought humans have objective huge value, then there would be no rational argument to think animals don't have similar value as well. And a lot of people seem to think that way, and when asked why they think so, answer with some of the bad arguments I wrote about in OP.

If they said morality is always subjective, and they (irrationally) believe in humans as a higher species, my thought would be pretty much the same as SNOWBALL138's thought regarding Hitler's thinking of Aryan race as a higher race.

Generally though, instead of admitting to Hitler-type thinking, people seem to base their subjective view on morality of (ab-)using animals the way we do today on incorrect (outdated) scientific information about animal psychology, incorrect knowledge about animal treatment today, social norms, Christian speciesism (belief in humans as a higher species) and emotional speciesism.