is being human not a permanent situation? Why eres and not es? if it was humane then eres.
Because it's using "tú" and not "usted". Remember the two ways of the second person in singular.
Sorry, actually there are three forms of the second person in singular: "tú", "usted" and "vos". I don't know if Duolingo teaches you (or accepts) this last form.
"eres" is a form of 'ser'
this kindof sounds awkward again