You and I are animals. We are also vertebrates, mammals, and primates. These facts are often masked by our language. In common usage ‘animals’ only refers to animals who aren't human . So if you were asked to name a favorite animal, ‘humans’ would be considered a very strange, perhaps nonsensical, response.
Language indicating that humans are animals isn't just taxonomically accurate. It also challenges an aspect of speciesism: people not admitting they are animals or not feeling comfortable with the fact. These learned behaviors have a rational basis. Denying kinship with an oppressed group makes it easier to rationalize their plight.
This problem of humans being excluded from the term animals has existed for centuries. Obsolete solutions include ‘sub-human animals’ and ‘lower animals’:
“I believe I have something else in common with sub-humans — my hyper-sensitivity. I am convinced that animals are more sensitive than humans, and that the reason people do not know this is simply because they are not sensitive enough to feel that it is so. — Margaret Thorne in 1974 
“[A] belief that in years to come there will be a recognition of the brotherhood between man and man, nation and nation, human and sub-human, which will transform a state of semi-savagery as we have it, into one of civilization, when there will be no barbarity such as warfare, or the robbery of the poor by the rich, or the ill-usage of the lower animals by mankind. — Henry Salt in 1939 
Most, despite knowing that humans are animals, always speak and write of humans and animals as two unrelated categories. In other words, their ‘animals’ means animals who aren't human. A small percentage of advocates use ‘nonhuman animals’ or ‘other animals’ — by far the most popular alternatives — intermittently with the conventional ‘animals’. Why not consistently? Some argue that accurate language can be clumsy, confusing, or annoying. I'm sympathetic to these concerns but rarely swayed by them . Like very few advocates, I almost never use ‘animals’ to mean animals who aren't human.
Rather than discuss the importance of alternative language, the remainder of this essay evaluates the meaning and suitability of the terms currently in use. I argue that ‘nonhuman animals’ always and unmistakably refers to animals who aren't human. ‘Other animals’ only refers to animals who aren't human in some situations. It has a wide range of possible meanings, so the phrase should be used with care. This essay was sparked by reading a statement by David Nibert, professor at Wittenberg University :