In fact, they make a part-Indian like Johnny Depp look like Sitting Bull. I'm guessing they were chosen primarily for their "hotness."
But Russell Means and Tonantzin Carmelo are billed ninth and tenth in the cast, so Unearthed isn't totally devoid of real Indians. For what it's worth.
As for the plot, releasing a creature from an archeological site sounds typical but not stereotypical. Unless the site is supposed to be an Indian burial ground. Then it's stereotypical.
Also, choosing a beautiful young starlet to play the Indian woman is stereotypical casting. It's another example of the Indian princess mentality that's persisted for centuries. We can't have Indian women who aren't gorgeous by Hollywood's standards, can we?
For more on the subject, see The Best Indian Movies.