simple

absolute arcadian austere barest bare benighted blockheaded careless chaste childlike classic cleanest cleanest clean clean clearer clearest clear commonest common credulous crude crudest daft daftest denser dense dimwitted doltish doting dopey down to earth downright dry dull duller dupable easiest earthy easy as pie easier easy effortless elegant facile familiar fatuous featherbrained feeble-minded foolish forthright gullible guileless harmless homelike homely homespun homey humble humble humblest humblest ignoble imbecile imbecilic ingenuous innocent literal loopy low lowly main mere mindless modest modest more modest more modest more primary more primary more virginal more familiar more natural more elegant most primary most primary more readable more understandable most virginal naked naive 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 primary/prime primitive primest primary purest pure readable rudimentary rude rural rustic rustic self-effacing senseless shallow shallower sheer simple-minded silly single slower slowest slow soft soft softer softer softheaded spartan spontaneous stark stupid thick-witted tomfool unaffected unassuming uncomplicated understandable undiluted unimposing unintelligent unoffensive unqualified unprocessed unostentatious unmitigated unpretentious unsuspecting unvarnished unwashed user-friendly unworldly very voluminous virginal