not yet fully developed; too soon (because not ready)

young, inexperienced

silly

stupid

not apt or relevant

incompetent; not suitable

(of behaviour, something said) causing no harm; not wanting to harm

harmless

without taste or flavour, without interest, spirit

dull, uninteresting

(of, suitable for) a young person

childish

connected with walking; a person walking in a street etc

everyday, dull

childish

childish

having to do with emotions (and not practical or sensible judgement); producing, expressing, (often too strong) feelings

emotional, romantic

(of remarks, ideas, opinions) ordinary and dull

silly, commonplace

not enjoyable

boring, uneventful

not entertaining

boring, uneventful