carefree, casual, dégagé, lackadaisical, nonchalant, unaffected, unconcerned, unfussy, unperturbed, untroubled, unworried

familiar, homey (also homy), informal

flexible, lax, lenient, permissive, pliable, pliant, soft

accessible, approachable

imperturbable, nerveless, unflappable, unshakable

amicable, companionable, comradely, cordial, genial, hail-fellow-well-met, hearty, neighborly, warm, warmhearted

careless, derelict, heedless, irresponsible, lazy, neglectful, negligent, remiss, slipshod, sloppy, sloven, slovenly, unfussy