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Synonyms for Unsophisticated (same or very similar meaning)

WordNet sense 1 (not wise in the ways of the world):

WordNet sense 2 (marked by or showing unaffected simplicity and lack of guile or worldly experience):
naif, naive

WordNet sense 3 (lacking complexity):

WordNet sense 4 (having few parts; not complex or complicated or involved):

WordNet sense 5 (awkwardly simple and provincial):
hick, rustic, bumpkinly

From the ODE community, based on WordNetadd/edit