na-adjective, noun which may take the genitive case particle 'no'
ordinary; typical; conventional; average
Describes something that is at the same level as most people or society in general, especially regarding lifestyle, behavior, or opinions. Often used in comparisons or to express conformity.
His salary is about average.
I'm satisfied as long as I can live an ordinary life.
平均的 means 'average' in a statistical sense, whereas 世間並み carries a nuance of conforming to social norms.
Standard kanji spelling; the most common written form.
Kana-mixed variant; less common but still encountered.
Abbreviated kanji form; rarely used.
Formed from 世間, “society; ordinary people,” and 並み, “on the usual level,” hence “ordinary by general social standards.”