No in this case "an" is pretty much meaning in. It is more expressing a connection really.
Duolingo also uses example sentences like "ich bin Jude", "ich bin Christ", "ich bin zweiundachtzig Jahre alt", and "der grüne Bär ist unsichtbar". What makes this example statement so special that it should be removed, even if it may be false from the perspective of some users?
Does it offend you that this sentence exist at all, or that you have to repeat it?
I see there were a few angry responses to this comment, but I would agree that it's a sentence that unneccessarily makes the user uncomfortable. Maybe just switch it to the 2nd or 3rd person? That way any discomfort is easily avoided.