Explained in Detail - 41:14
"Messengers went to them from before them and behind them, saying: "Do not serve or serve other than Allah". They said, "If our Lord had willed, He could have sent down an angel. Therefore we do not believe in the message you bring"."
Why a human messenger?
The Bee/16:43
We did not send before you as messengers except men, those who walked on two feet, and We revealed to them. Ask the experts if you do not know.
The Prophets/21:7
We did not send before you any messenger except to men, but We revealed to them; ask the experts if you do not know.
Prophet Joseph/12:109
We did not send before you except men whom We revealed to you from among the inhabitants of the cities. Do they not travel through the earth and see the fate of those before them? Is the abode of the Hereafter better for the righteous; do you not understand?
The Pilgrimage/22:75
Allah chooses messengers from angels and mankind. Surely Allah is All-Hearing, All-Seeing.
The Night Journey/17:95
"Say: "If there were angels inhabiting the earth, We would have sent to them an angel from heaven as a messenger."