To clarify the answer to the foregoing question, we must take notice of the following points:
1.  Although man does not have exhaustive knowledge of various kinds of creatures, he can, through revelation and divine reports, acquire knowledge and information about various beings, their position and ranks. For instance, go through the following narration:
Abdullah bin Sanan says that he asked Imam Sadiq (AS) whether angels were superior or the children of Adam. Imam Sadiq (AS) quoted the Commander of the Faithful, Ali (AS) in response: "God placed intellect in the angels without lust, He placed lust in animals without intellect and in man he placed intellect along with lust. Hence, if human intellect takes over his lust, he will be superior to angels and if his lust takes over his intellect, he will be lower and meaner than animals."[1]
2. According to us, it is inferred from the Quranic verses and narrations about creation of man that he is superior to all other creatures in this mode of existence – including all earthly and celestial beings.  This is entirely because of the features and characteristics which man possesses as will be enumerated below:
a) The first characteristic particular to man is the divine spirit he is gifted with. It is a feature which man alone possesses. God, the Exalted, says: "So when I have made him complete and breathed into him of My spirit, fall down making obeisance to him."[2]
b) Angels prostrating themselves before man: "And when We said unto the angels: Prostrate yourselves before Adam, they fell prostrate, all save Iblis."[3]
c) Man is God's vicegerent on earth: This is yet another characteristic making him an outstanding creature among other beings including angles and jinns: "And when your Lord said to the angels, I am going to place in the earth a vicegerent…"[4]
d) Another characteristic of man is that he is the goal or purpose of creation. In reality, other entities have been created to be at man's service and for his benefit. "And He has made subservient to you whatsoever is in the heavens and whatsoever is in the earth, all, from Himself."[5] "O son of Adam, I have created Adam for you and you for Myself."[6] This is perhaps because man has the capacity to attain the highest degree of perfection and merit after he has been in the lowest mode of existence in the world of nature. He will be united with God and will disappear in Him. This is a characteristic prerogative of man only.
e)  The presence of the best of creatures Prophet Muhammad (S) among the present human beings is the best sign indicating man's superiority over other creatures including angels and jinns.
Given the above details, it is very clear that man is the best of creatures in the entire universe.  As for creation of a being superior to man, philosophically speaking, it is not essentially prohibited but it is unlikely. To clarify it further, God says in Surah al-Baqarah while pointing out the reason and stages of the creation of Adam in a discussion with angels:
"اذ قال ربک للملائکة انی جاعل فی الارض خلیفة"[7]
"And when your Lord said to the angels, I am going to place in the earth a vicegerent (khalif)."
In Arabic language, the word "Khalifa" means an imam (leader) without anyone being superior to him.[8] Taking this meaning into consideration and in view of the fact that God, the Exalted, does not make use of a word unless without considering its meanings and applications, therefore, we come to the conclusion that by giving man this title, God, the Glorified, made him excel everything that exists and shall be created in future. If God decides to create a creature more sublime and dignified than man, then man will be dismissed from his position as a vicegerent of Allah.
In addition, the presence of Prophet Muhammad (S) and infallibles, who are the reasons for creation of other creatures and who were undoubtedly at the highest degree of perfection and human potentials, indicates that it is unlikely for any other creatures  to be superior to man.

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