1)
Why does it say "Gam"?
1.
Malbim: This includes all classes of people - honorable and lowly, rich and poor - all are foolish about this.
2)
Who are "Bnei Adam"?
1.
Rashi: Sons of Avraham, who is called "ha'Adam ha'Gadol ba'Anakim" (Yehoshua 14:15) - Bnei Yishmael and Bnei Keturah.
2.
Radak: They are people of a low level.
3)
Who are "Bnei Ish"?
1.
Rashi: Sons of Noach, who is called "Ish Tzadik" (Bereishis 6:9).
2.
Radak: These are great people, like "Gid'on 1 ben Yo'ash Ish Yisrael" (Shoftim 7:14).
1
He was one of the three 'Kalei Olam' (Rosh Hashanah 25b)! I.e. among leaders of Yisrael, he was among the lowest. (PF)
