Bereshis seems to imply that Adam was literally the first human being (at least according to the normal translation). Do any commentators (preferably not modern ones) disagree with this?
R Israel Lipschitz, the Tiferet Yisrael, author of a classic commentary on the Mishna, wrote in 1842 in his essay Ohr HaChayim, that there were other men before Adam
The Kabbalah teaches that in ancient times several worlds of living creatures were created and destroyed on Earth. Humans were first created 974 generations before Adam. With Adam, the world was renewed to suit the light of Torah, and mankind became refined enough to receive the Torah (from here)
See also this longer description (taken from this essay on YUTorah, pp. 23ff)
In my humble opinion, those men who lived in prehistoric times, called Pre-Adamites in their [i.e., the scientists’] language, are really the people of a world before Adam of our world. These are the 974 generations mentioned in in Shabbat (88b) and Hagigah (13b) who were created before this world. ... Since their world was corrupt, they were cut off 26 generations before reaching twenty-six generations. ... If we reckon that each generation is seventy years, this means that their world was destroyed after 6,818 years from its creation. These twenty-six generations that were missing in their world were completed from Adam to Moses our Teacher ... in which the world was prepared and refined well in order to receive the Torah.