Yep, I take Americans and feed them to the lion that the girl owns. ;)
You can take the English course if you do a reverse course of a language. For example En->Fr and the reverse course would be Fr->En. Just go here (https://www.duolingo.com/courses) select a native language other than English and then pick your reverse course.
But I wouldn't say that American is a language. It's an English dialect that Duolingo happens to use as the flag for the English course because it's the type of English they teach.
I also have a lion! he is called Aslan! he loves "the world in my aunts closet" XD