simple

absolute arcadian austere bare barest benighted blockheaded careless chaste childlike classic cleanest cleanest clean clean clear clearest clearer commonest common credulous crudest crude daft daftest dense denser dimwitted doltish dopey doting downright down to earth dry dull duller dupable easy as pie easy earthy easiest easier effortless elegant facile familiar fatuous featherbrained feeble-minded foolish forthright gullible guileless harmless homespun homelike homely homey humblest humblest humble humble ignoble imbecile imbecilic ingenuous innocent literal lowly loopy low main mere mindless modest modest more readable more familiar more elegant more understandable more primary more primary most virginal more modest more modest more virginal more natural most primary most primary naked naive natural nominal nothing to it nothing to it open and shut/open-and-shut oafish open-and-shut ordinary oversimplified pastoral perfect pellucid plain plain primary/prime primitive primary primest purest pure readable rude rudimentary rural rustic rustic self-effacing senseless shallower shallow sheer simple-minded single silly slower slowest slow soft soft softer softer 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