Ah...yes well...Alternate dimensions you see. Where I come from the only err...people like us on Earth are primitive four legged creatures much smaller then you or I. The predominate species on the planet is a large two legged creature known as Humans.

Naturally the term "alien" is subject to the planet you are from...but technically you could say to Earth yes I am an alien, though in this world we all are in a way.

Oh...and some people have been here three years or longer...the way we are sent home appears almost random.