Simply put, the responsibility of Bani Adam is to do what the Creator would have done Himself had He not placed His vicegerent on the earth. What would Allah have done on this earth had He not put His representative or Khalifa here? The answer is that He would have ruled and administrated this world as He rules and administrates His vast creation, the universe. For the earth, however, He chose to delegate this responsibility to man. So to rule and administrate the affairs of this world on His behalf is the duty and responsibility of the Khalifa i.e. mankind.
Now, how man will do it? To this end, Allah supplied a complete set of directions, inclusive of all aspects of regulation that He Himself would have used if He were to govern this earth Himself. He supplied these guidelines and instructed mankind to regulate their lives with it; as this would be the Ebadat they were created to perform.
This entire universe of the Maker is regulated by a strict code of discipline; each creation carries out the specific job it has been ordained without a moment’s interruption or hesitation.
Among all of Allah's creations there is not one object that possesses even an atomic weight of self-will or will-power. But with the creation of Adam for the first time Allah created something that could break this discipline for this new creation was in possession of something so extra ordinary that not one from His entire universe full of creation were gifted with. Allah blew from His soul into Man,
and this the latest creation rose far higher in rank than any of the others, became the "Ashraf-ul-Makhlukat- the most honored in the whole creation"; for along His soul came one and all of His sifats or attributes including that of free will which no other creation had any idea about. Allah's sifats or attributes are endless but what was transferred to man with the breath was everything in very small amounts; a small drop from the ocean, incomparable or entirely insignificant in comparison to the mighty ocean itself, but still a drop from the same source, of the same chemical composition. The reason why He blew into Adam from His soul which contains every attribute of His, though in infinitesimal quantity is that it is necessary that to function properly a representative, agent, a Khalifa must have the same type of power and authority as the employer. He regards the breathing from His soul into Adam as His trust (Amanat) to Man.
Now we see that Allah is first and foremost the only Elah, the only one to be obeyed and the only Ma'bud, only one to be worshipped, that is to be served. First comes the acceptance of Him as the Elah, only sovereignty, and then come to serve Him (Ebadat) by governing this world on His behalf by His rules, regulations, laws, and orders. When this is carried out properly, man does the job he was created for, performing the actual Ebadat (service) expected from him. The result of changing the meaning of the word 'Elah' (He, who is to be obeyed) in the Kalema into 'Ma'bud' (He, who is to be worshipped, served), is that the huge population called Muslims but de facto Kafer (disbeliever, rejecter), Moshreq (polytheist), fasek (disobedient), zalem (wrong doer), Monafeq (hypocrite) and hence cursed by Allah, Malayeks (angels) and people. Furthermore, man has not remained a believer in Elah or Ma'bud either as he has accepted the Dajjal as his Elah and Ma'bud in his collective life. Let us observe what in man’s concept Ebadat is that they are so busy with. As man was appointed the Khalifa of Allah, it is taken that they were to govern this earth according to the rules, regulations and directives provided by the Maker himself. This is the real Ebadat (service). However, to this present populace Ebadat is to recite Kalema with wrong meaning of the word Elah, to say prayers, to pay Zakah, to perform Hajj and to fast in the month of Ramadan. In doing these they are thinking that they are performing proper Ebadat and are very good Muslims. Yet in the true sense, to serve Allah is to work as His Khalifa by doing things on His behalf; so, as Allah's Khalifa, His vice gerent, if Khelafat is their Ebadat - then the question now arises is does Allah say prayer (namaz), pay Zakah (poor-due), perform Hajj, observe Saom (roza), or get up in middle of the night to say Tahajjud prayers?
Is He in the practice of these or any other good deed that this population thinks of as Ebadat? Needless to say, He doesn't. All these good deeds do not fall within the category of real Ebadat, i.e. Khelafat. What then are these if not Ebadat? These are the practices He has ordered as mandatory so that the entire Ummah reaches a uniform level of discipline.
 See Ayat 56 in Sura Dhariyat where Allah is saying "I have not created the Jinn (invisible beings) and Men to any end other than that they may worship (Ebadat) Me."
 The Qur'an- Sura Hejr-29, Sura Sajda- 9, Sura Saad-72.
 The Qur'an- Sura Ahzab: 72.