It's one of those two Jews three opinions things, but yes there are some sources/commentaries that basically say there are/were other humans and that the Adam Eve story, and the rest of the creation story for that matter, isn't meant to be taken literally. And I don't mean modern sources. Rabbi Shlomo Yitzchaki, (Rashi), for example, says in his commentary on the first chapters of Genesis that if you really think God created everything in literal six literal 24-hour days and the like that you're a moron and no one should listen to you on anything else. I'm paraphrasing, but Rashi's commentary is pretty much foundational to Torah study and dates from the 11th century. See also: That line in the movie Dogma about going through five Adams before getting it right. That's a reference to more than one Jewish source on the subject. Hope this helps.