adjective

(of an adult) having the good qualities, such as innocence, associated with a child.

she speaks with a childlike directness

innocent,artless,guileless,simple,unworldly,unsophisticated,green,inexperienced,naive,ingenuous,trusting,trustful,unsuspicious,unwary,unguarded,credulous,gullible,easily taken in,unaffected,without airs,open,frank,uninhibited,natural,spontaneous,down-to-earth,wet behind the ears