To answer the question "why did GOD create a humankind"it must first be determined from which perspective thequestion is being asked.From the point of view of GOD it would mean."what caused GOD to create human beings?"while from the human point of view it would mean "for for the purpos did GOD create humans?"Both point of view represent aspects of teh intriguing question"why do i exist?"
this question shouldbe asked because humankind is not, in fact, the greatest creation.GOD says in chapter of the final revelation.
"Indeed, the creation of the heavens the earth is greater than of humankind, but most of mankind do not ralize it". (qur'an 40:57).
the defination of creator in chapter ash-shoora of the final revelation, he states:
"There is nothing like Him and He is the all hearer and the all-seer"(qur'an 42:11)
in surah al-ikhlas
say: he is allah, the one and only
Allah, the eternal and absolute;
he begetteth not, nor is he begotten
and there is non like unto him. (qur'an 112).