But there are important differences between humans and animals. Since we are talking about populations of organisms (e.g. all pigs and all humans) the boundarie

But there are important differences between humans and animals. Since we are talking about populations of organisms (e.g. all pigs and all humans) the boundaries can look rough and fuzzy, but not so fuzzy that you can claim there is a continuous spectrum of organisms from any given animal species to humans. You can't just raise or teach a particularly gifted chimpanzee to be a human because there are vast biological differences, one of which is our unmatched talent for putting ideas into each other's heads. Therefore, despite the many similarities between humans and various animal species, it's fair to say that we are separate from animals. This doesn't mean it's okay to treat animals badly, and there are still good and moral justifications for veg*ism even if you accept that humans and animals are separate, but I think it's important to resist the temptation to ascribe human qualities to animals. We really are separate.