WordNet sense 1 (of little substance or significance):

superficial

WordNet sense 2 (not important or noteworthy):

insignificant, unimportant

WordNet sense 3 (not serious in content or attitude or behavior):

frivolous

WordNet sense 4 (not exceptional in any way especially in quality or ability or size or degree):

ordinary

WordNet sense 5 ((informal) small and of little importance):

lilliputian, little, niggling, petty, picayune, piddling, piffling, fiddling, footling

WordNet sense 6 (too small or unimportant to merit attention):

inconsiderable