Human or, Humans

Both of these are actually correct Vicka.

'we are human'-- 'human' is a predicate adjective, a subject complement. 

'we are humans'-- 'humans' is a noun complement of the subject. 

Human or, Humans

Hi Vika, 

They are both correct English but have different meanings; 

We are all human = Here you are saying, we are all human, which is to say we all make mistakes, get tempted, fail to go to the gym, eat too much!  etc. 

We are all humans = Here you are saying we are all human beings.