simple

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