Role of humility in Islam

Humility is when a person does not see himself as being better or above other people because of frivolous reasons like social standing, education, citizenship, or even color.
As for believing one is better than another person due to religious reasons, then in some cases this is permissible, and in other cases, it's an obligation. For instance, Muslims should believe Allah has given him 'Izza over the Kaafir. This has been established in the Quran in many places:
Allah says, ".and to Allah belongs all honor (I'zzah), and to His Messenger, and to the believers.." Sura 63 Ayat 8
God created human beings to worship Him and a practising Muslims, in essence, should be able to worship God in every second, of every hour of every day. Islam is a way of life and it means nothing more, or less, than submission to the One God. "And I (God) created not the jinn and humans except they should worship Me Alone." (Quran 51:56)
The concept of God in Islam describes Him as the most Merciful and the most Loving and whatever He prescribes for humankind is in the best interest of humankind Submission to the will of God is a pathway to purity, to peace and ultimately to Paradise. The word Quran most frequently uses to describe worship is Ibadah. Ibadah is the root of the word 'ubudiyyah, which means to express ones humility or humbleness, and as with most Arabic words there are many shades of meaning. Ibadah involves more than an awareness of humility.
It is the complete sense of humbleness that overcomes one who is totally submitted to the will of God, the Almighty. Worship is submission to God, the essential part of submission is humility. "So glorify the praises of your Lord and be of those who prostrate themselves (to Him)." (Quran 15:98)
Humility can guide us to Paradise, just as its opposite, arrogance, kibr in Arabic, can only lead us into Hell. It is Satan's arrogance that caused his expulsion from Paradise; when he refused to humbly obey God's command and prostrate before Adam, the father of mankind, he condemned himself and his followers to Hell.
True piety or righteousness is not achievable without cultivating a sense of humility. "And turn not your face away from men with pride, nor walk in insolence through the earth. Verily, God likes not each arrogant boaster." (Quran 31:18)
Humility comes from knowing about God and recognising His greatness, venerating Him, loving Him and being in awe of Him; and it comes from knowing about oneself and one's own faults, and weaknesses. God gives this characteristic to those who struggle to become close to Him through deeds of piety and righteousness..
Prophet Muhammad (peace be upon him) was truly submitted to God; his character was one of complete humility and based on sincere trust in God. He was a model of kindness and humbleness. In fact, the characteristics displayed by Prophet Muhammad (peace be upon him) were the exact opposite of pride and arrogance. Every aspect of his life reflected humbleness, even his walking, talking, sitting or eating.
The Prophet did not behave towards others as if he was better than they were, nor did he spurn manual work. The companions of the Prophet and the early generations of Muslims understood the concept of humility. They behaved humbly towards God and mankind because of their love for God, and their fellow man, and fear of punishment in the Hereafter.
During his Caliphate, Syedna Omar ibn Al Khattab was marching upon Damascus with his army. Abu Ubayda was with him. They came upon a little lake. Syedna Omar descended from his camel, took off his shoes, tied them together, and hung them on his shoulder. He then took the halter off his camel and they entered the water together.
Seeing this in front of the army, Abu Ubayda said, "O Commander of the Believers! How can you be so humble in front of all your men?" Syedna Omar answered, "Woe to you, Abu Ubayda! If only anyone else other than you thought this way! Thoughts like this will cause the downfall of the Muslims. Don't you see we were indeed a very lowly people? God raised us to a position of honour and greatness through Islam. If we forget who we are and wish other than the Islam which elevated us, the One who raised us surely will debase us."
The one who is truly humble is the one who is truly blessed. Every time he feels superior to others, he remembers God, the Most Great and Omnipotent, and humbles himself in true submission. "And the slaves of God are those who walk on the earth in humility and calmness, and when the foolish address them (with bad words) they reply back with mild words of gentleness." (Quran 25:63)