Translation

ningen means "Human" in English.

ningen written with kanji is 人間.
These are jouyou kanji 常用漢字, taught in the second year of shougakkou 小学校.
ningen written with katakana is ニンゲン.
ningen written with hiragana is にんげん.
Romaji ni n ge n
Hiragana
Katakana
Kanji
School Level 小1 小2
ruijin'en 類人猿.