Any cognate with Spanish camisa?
Appears so. They are probably loanwards from Arabic.
Cf. Arabic for shirt, قميص (qamis).
oh no! be careful, he has a shirt!
he has (only) one shirt....
he is a shirt!! surely not
No -- he has a shirt.
Did Duolingo show you "He's a shirt"? It sometimes automatically contracts has to 's whether it makes sense (He has given me the book already = He's given me the book already) or not (He has a cat =? He's a cat).
Yes it did say 'he is a shirt
It didn't say he is a shirt for me