simple

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