This question has a simple answer: God cannot be like man nor any creation because it is not befitting for God to be like His creation – neither in physical form nor through His actions – as God is beyond and above His creation. Allah has defined His attributes in the Quran which helps us understand how He is. Allah says in the Quran; in Surah Ikhlaas, chapter 112, verses 1-4.

Say: He is Allah, the One! Allah, the Eternal, Absolute. He begets not, nor is He begotten. Nor is there to Him any equivalent.  

Allah is absolute and everlasting.  He is perfect while his creation is weak and imperfect. He is free from all needs. He is neither born nor does He have offspring. On the contrary, human beings have needs, they are born and they face death. Allah is eternal while His creation has a beginning and an end. So, if one assumes that God can take human form, he agrees to the notion that God has flaws just like humans or other creations. It is disparaging to give God human traits when He has no similarities to His creation. As Allah says: 

 [He is] Creator of the heavens and the earth. He has made for you from yourselves, mates, and among the cattle, mates; He multiplies you thereby. There is nothing like unto Him, and He is the Hearing, the Seeing. Surah Shura, chapter 42, verse 11.

Some people might say “If God can do everything why can’t He take human form or form of any other creation?” First and foremost, God does what He wills and what suits His majesty and He is capable of doing all things without any assistance. So why would He take a human form when He is the creator of man in the first place. As mentioned in Surah Baqarah, chapter 2, verse 255:

Allah - there is no deity except Him, the Ever-Living, the Sustainer of [all] existence. Neither drowsiness overtakes Him nor sleep. To Him belongs whatever is in the heavens and whatever is on the earth. Who is it that can intercede with Him except by His permission? He knows what is [presently] before them and what will be after them, and they encompass not a thing of His knowledge except for what He wills. His Kursi (Chair) extends over the heavens and the earth, and their preservation tires Him not. And He is the Highest, the Greatest. 

Allah’s magnificent qualities mentioned in this verse connote that He has no reason to take human form. His will prevails in the heavens and the earth and He can do whatever He wills from where He is. So, we conclude by saying that it is not befitting for Allah to take form of any of His creations, be it man or any other thing. Allah knows best. May Allah guide us.