While the generic character that the name of Adam has in the older parts of Scripture, where it appears with the article ("the man"), was gradually lost sight of, his typical character as the representative of the unity of mankind was constantly emphasized (compare Sanh. iv. 5; the correct reading in Tosef., Sanh. viii. 4-9):
"Why was only a single specimen of man created first? To teach us that he who destroys a single soul destroys a whole world and that he who saves a single soul saves a whole world; furthermore, in order that no race or class may claim a nobler ancestry, saying, 'Our father was born first'; and, finally, to give testimony to the greatness of the Lord, who caused the wonderful diversity of mankind to emanate from one type. And why was Adam created last of all beings? To teach him humility; for if he be overbearing, let him remember that the little fly preceded him in the order of creation."
In a dispute, therefore, as to which Biblical verse expresses the fundamental principle of the Law, Simon ben 'Azkai maintained against R. Akiba—who, following Hillel, had singled out the Golden Rule (Lev. xix. 18)—that the principle of love must have as its basis Gen. v. 1, which teaches that all men are the offspring of him who was made in the image of God (Sifra, Ḳedoshim, iv.; Yer. Ned. ix. 41
c;
Gen. R. 24). This idea, expressed also by Paul in his speech at Athens, "[God] hath made of one blood all nations of men for to dwell on all the face of the earth" (Acts, xvii. 26), found expression in many characteristic forms.
ADAM - JewishEncyclopedia.com