Because it's a fictional story, about a fictional planet, in which exactly one earth "animal" exists ... and that animal is a human being. It makes no more sense in Animal Kingdom than a Star Wars land or a Flash Gordon land - they are science fiction movies set on a different planet.
Disney can do one of two things: (a) They can build a attraction/land that people hear about and immediately say "Well, that just makes sense" (for example, a Brazilian pavilion in WS, or a Star Wars land in DHS, or a Snow White mine train in Fantasyland) ... or (b) they can decide they want to build something that does not instinctively make sense and go about the business of convincing the Disney fan community that if they squint real hard and cover one eye and only think about one minor aspect of the theme park, it kinda sorta fits.
In this instance, they have decided to go with option B because they panicked several years ago and spent money for an intellectual property and now they'd rather throw good money after bad than admit they made a mistake. The first step in "convincing the Disney fan community" is nice concept art coupled with zero discussion of the fact that it's a sci-fi film about aliens being shoehorned in their Earth-based animals zoological theme park.