If tauntauns (i.e., creatures relevantly like this) existed, they would be animals. If tauntauns existed, they wouldn't be members of the kingdom Animalia, because the kingdom Animalia is a clade, and Tauntaun's would presumably be products of alien evolution rather than descendants of earth animals. Since it's possible for tauntauns to exist, it follows that it's possible for there to be animals that aren't members of the kingdom Animalia.
Another example. Suppose a species of water plant evolved to have descendants whose behavior and build closely resembles a hippotamus. The resulting species would still be a member of the kingdom Plantae, since the Plantae are a clade, and not of Animalia. But I think it would be an animal. Would it be a plant as well? Maybe—maybe it would be both plant and animal.
The concept of an animal goes beyond actual earth biology. Now, here's an interesting question. We are rational animals. Could there be rational embodied non-animals, e.g., rational plants that, unlike the hippopotamus-like plants of my example, are not animals? There would be little reason for a non-animal to evolve intelligence, but an extremely unlikely series of chance mutations is not impossible just because it's unlikely.
Are questions about what is and what isn't an animal substantive questions? Or is it just a matter of drawing arbitrary non-joint-carving boundaries?