[Al-Baqarah 2.30] Behold, thy Lord said to the angels. "I will create a vicegerent/ khaleefatan on earth." They said. "Wilt You place therein one who will make mischief therein and shed blood?- whilst we do celebrate Your praises and glorify Your holy (name)?" He said. "I know what you know not."


[Al-Baqarah 2.30] Wa-ith qala rabbuka lilmala-ikatiinnee jaAAilun fee al-ardi khaleefatan qalooatajAAalu feeha man yufsidu feeha wayasfiku alddimaawanahnu nusabbihu bihamdika wanuqaddisu lakaqala innee aAAlamu ma la taAAlam

khaleefatan with a tanween is plural and indefinite

khaleefatan means to be in succession, one who comes after or stands with someone who PRECEDES them

Humans EXISTED BEFORE any individual named 'Adam'

Adam is from the root word Adama meaning brown, human being, man, person, intelligent person, person in possession of different powers, person who is created from different substances, one who has heirs

************************************************** *************
[Al-Baqarah 2.31] And He taught Adam the nature of all things; then He placed them before the angels, and said. "Tell me the nature of these if you are right."


Wa `Allama 'Ādama Al-'Asmā'a Kullahā Thumma `Arađahum `Alá Al-Malā'ikati Faqāla 'Anbi'ūnī Bi'asmā'i Hā'uulā' 'In Kuntum Şādiqīna

************************************************** *************

Thus when Allah is referring to Adam and the creation of humans Allah is NOT referring to a specific person in human history.

Allah is referring to the succession of human creation and the behaviors, personality, intellectual and spiritual development of the human creation.