I ran into a typo in Japanese 1, level 12 “Cracking Kanji”.
The bolded sentence said: “わたしはにほんじんではありません” and the correct choice out of six was indeed “I am not Japanese.”
But the little box under the bolded sentence said: “私はイギリス人ではありません” which (I’m assuming whoever replies to this can understand) translates to “I am not English.”