It is probably the case that a classifier set always includes a contrast human/nonhuman or animate/inanimate … A gender/noun class system almost always includes a contrast human/nonhuman or animate/inanimate, and even if it does not there will be a distinction of this type elsewhere in the grammar.
Standardized
(i) IF there are classifiers for other contrasts, THEN there are ones for the contrast human/nonhuman or animate/inanimate;(ii) IF there are genders or noun classes for other contrasts, THEN there are ones for the contrast human/nonhuman or animate/inanimate.(iii) There is a contrast human/nonhuman or animate/inanimate recognized by some grammatical forms (such as interrogative pronouns) or rules.