Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904]
THE homonymous term adam is in the first place the name of the first man, being, as Scripture indicates, derived from adamah, "earth." Next, it means "mankind," as "My spirit shall not strive with man (adam)" (Gen. vi. 3). Again "Who knoweth the spirit of the children of man (adam)" (Eccles. iii. 21); "so that a man (adam) has no pre-eminence above a beast" (Eccles. iii. 19). Adam. signifies also "the multitude," "the lower classes" as opposed to those distinguished from the rest, as "Both low (bene adam) and high (bene ish)" (Ps. xlix. 3).
It is in this third signification that it occurs in the verses, "The sons of the higher order (Elohim) saw the daughters of the lower order (adam)" (Gen. vi. 2); and "Forsooth! as the humble man (adam) you shall die" (Ps. lxxxii. 7).