Although the word is now incorrectly interpreted as "masculine," the true root is genderless, coming from the Sanskrit manas, which means mind, and also O.E. man, mann "human being, person," from P.Gmc. *manwaz (cf. O.S., O.H.G. man, Ger. Mann, O.N. maðr, Goth. manna "man"), from PIE base *man- (cf. Skt. manuh, Avestan manu-, O.C.S. mozi. In Gnosis, the term man retains its genderless meaning and points directly at the mind. This is supported in scripture, as the first person is called Adam, an androgynous being who is male-female.
"And Elohim said, Let us make man in our image, after our likeness: [...] So Elohim created man in his [own] image, in the image of God created he him; male and female created he them." - Genesis 1
"We learned that man has names in different stages, for he is called Adam (man), Gever (male man), Enosh (human), Ish (person). The greatest is Adam, as written, "So Elohim created man (Heb. adam) in His own image" (Beresheet 1:27), and, "for in the image of Elohim made He man (Heb. adam)" (Beresheet 9:6), instead of using Gever, Enosh or Ish. Rabbi Yehuda said, in that case, it is written, "If any man (Heb. adam) of you bring an offering to Hashem" (Vayikra 1:2). Who needs to bring an offering? Only whoever sins who is of a lesser level. Nevertheless it is written, Adam.