simple

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