YOU SAID:
i am a twelwe year old human being
INTO JAPANESE
私は12歳の人間です
BACK INTO ENGLISH
I am a 12 year old person
INTO JAPANESE
私は12歳です
BACK INTO ENGLISH
I am 12 years old
INTO JAPANESE
私は8年生です
BACK INTO ENGLISH
I am 12 years old
That didn't even make that much sense in English.