should the an adjective 0r a noun come after the be verb?
since "we" is plural, "human" should be plural too? Not necessarily; see below
but can it also be adjective "human" short for "human (being)" Yes
we can get hurt
we are humans We are humans [[short form for "human beings"] / We are human beings
we are human We are all human [[ member of the family Hominidae]]