simple

absolute arcadian austere barest bare benighted blockheaded careless chaste childlike classic cleanest cleanest clean clean clear clearest clearer common commonest credulous crude crudest daft daftest denser dense dimwitted doltish dopey doting downright down to earth dry dull duller dupable easy as pie easiest earthy easier easy effortless elegant facile familiar fatuous featherbrained feeble-minded foolish forthright guileless gullible harmless homelike homely homey homespun humblest humblest humble humble ignoble imbecile imbecilic ingenuous innocent literal loopy low lowly main mere mindless modest modest more familiar more elegant more readable more understandable more modest more modest more primary more primary more natural more virginal 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 primary/prime primitive primest primary purest pure readable rudimentary rude rural rustic rustic self-effacing senseless shallower shallow sheer silly simple-minded single slow slowest slower softheaded soft soft softer softer 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