I agree, I would be pretty sure of that one being a cockerel.
If you want, show pictures of the other ones?
He may show other signs soon, like trying to crow.. but most roosters don't try until much older...
sorry, it looks like a boy to me also... that comb and color on it plus there seems to be a lot of white on those feathers. if the others seem much darker than him overall, as if the feathers are in reverse pattern than his- black with white instead of almost white with black bars(like on his...