na·ive
/nīˈēv/
adjective
(of a person or action) showing a lack of experience, wisdom, or judgment.
"the rather naive young man had been totally misled"
(of a person) natural and unaffected; innocent.
"Andy had a sweet, naive look when he smiled"
synonyms:   innocent, unsophisticated, artless, ingenuous, inexperienced, guileless, unworldly, childlike, trusting, trustful, dewy-eyed, starry-eyed, wide-eyed, fond, simple, natural, unaffected, unpretentious; More
of or denoting art produced in a straightforward style that deliberately rejects sophisticated artistic techniques and has a bold directness resembling a child's work, typically in bright colors with little or no perspective.