"...And I did it not of my own accord..." (18:82).
He did it not by his will according to this ayat,if it is an angle it wouldn´t be mentioned that he didn´t act on his own,so we can suppose that it is a Human but we have seen that the pronouns changed from "I" to "WE" in accompany with the use of the word"Lord",which makes this individual part of an divine gathering.
If he is a Prophet then he had a licence to kill a Person who might do harm to his parents"And as for the lad, his parents were believers and we feared lest he should oppress them by rebellion and disbelief. (80) "
If he is a holy Person like some say then he did a sin like the son of Adam who killed his brother Sura 5""For me, I intend to let thee draw on thyself my sin as well as thine, for thou wilt be among the companions of the Fire and that is the reward of those who do wrong." (29) "
I like the Statement of mine,that all this is dream,i came to this because of the fish and his former companion who suddenly disappered.