Also "theologically" according to the Jews their (older) Bible simply mentions "everlasting life" in the "Book of Daniel" at least century before the birth of Jesus. But they believe that the texts about Jesus written and collected by that newer sect that called them Christians simply don't prove that he's Messiah, as they are often based on misreadings of the Hebrew Bible, see for the example how NT came to use "the son of man" expression:
I'm just saying you can easily reconcile Ecclesiastes with the Christian notion of heaven by considering its context. I don't know if there's any such problem to be reconciled in Judaism.
My response was always to your claim that "the possibility of eternal life in heaven was only offered by Christ" and all my responses were to demonstrate that it's not "only by Christ" but an older and very known concept. They weren't supposed to help you reconcile that fact with your favorite theology.
I'm an atheist. I don't have a "favorite theology" but I understand some religions better than others, the original point of this discussion was a supposed inconsistency in one of them, and I find the subject interesting as an intellectual exercise. Now will you stop being needlessly confrontational?
http://www.jewishencyclopedia.com/articles/10342-man-son-of
Of course, there's more than one "theology," even among different "Christians."