"the only other possible explanation is an execrable bigotry"

Well, then I guess I'm an execrable bigot. I believe human life (at least 1 to 1) is more valuable than other forms of life on Earth. If I had to choose between saving an individual human being and an individual animal I would, in 100% of cases, choose the human. This isn't a religious conviction, simply, at least to me, a logical one.

I'm a pescatarian because I don't personally want to eat animals (though I don't see it as an absolute moral evil). I'm resolutely against all forms of animal cruelty (I don't even approve of horse-riding). I don't visit zoos because I find them grotesque. But I'd object to each of those scenarios a hundred times more if a human being were the subject.

I'm sure that some of the people who would agree with me would agree for religions reasons. But if you think the "only" other explanation for somebody valuing human life above animal life is religion, then I'm living proof that that's not true.