YOU SAID:
the oldest person in the world is your mum
INTO JAPANESE
世界で一番古い人はあなたのお母さんです
BACK INTO ENGLISH
The oldest person in the world is your mother
INTO JAPANESE
世界最高齢の人はお母さん
BACK INTO ENGLISH
Mom is the oldest person in the world
INTO JAPANESE
お母さんは世界最高齢
BACK INTO ENGLISH
Mom is the oldest in the world
INTO JAPANESE
ママは世界最古
BACK INTO ENGLISH
Mom is the oldest in the world
That didn't even make that much sense in English.