simple

absolute arcadian austere bare barest benighted blockheaded careless chaste childlike classic clean clean cleanest cleanest clearest clear clearer common commonest credulous crudest crude daft daftest denser dense dimwitted doltish dopey doting down to earth downright dry dull dupable duller easiest earthy easy as pie easy easier effortless elegant facile familiar fatuous featherbrained feeble-minded foolish forthright guileless gullible harmless homelike homey homely homespun humblest humblest humble humble ignoble imbecilic imbecile ingenuous innocent literal loopy low lowly main mere mindless modest modest more elegant more familiar more readable more primary more primary more natural more virginal more modest more modest more understandable most primary most primary most virginal naive naked natural nominal nothing to it nothing to it oafish open-and-shut open and shut/open-and-shut ordinary oversimplified pastoral pellucid perfect plain plain primitive primary/prime primary primest pure purest readable rudimentary rude rural rustic rustic self-effacing senseless shallow shallower sheer silly simple-minded single slow slowest slower softer softer soft soft softheaded spartan spontaneous stark stupid thick-witted tomfool unaffected unassuming uncomplicated understandable undiluted unimposing unintelligent unoffensive unprocessed unqualified unostentatious unmitigated unpretentious unsuspecting unvarnished unwashed user-friendly unworldly very voluminous virginal