I wouldn't say heaven is fundamental in the Old Testament, in fact it is barely mentioned (if at all, I'm not sure). Heaven certainly wasn't a major tenet of belief for the ancient Jews, much of the conflict between the Sadducees and Pharisees was because the former didn't believe in an afterlife.
As for the soul, IIRC that was more of a Hellenic idea and wasn't really in the Old Testament at all, at least not as we would understand it. Indeed, a quick wiki reveals:
"The only Hebrew word traditionally translated "soul" (nephesh) in English language Bibles refers to a living, breathing conscious body, rather than to an immortal soul"
Quote taken from this page.
Bookmarks