Vanderhoven, most of the OT saints are also mythological, clearly Abel, Noah, Melchizedek etc are. Isaak, Jacob and co. were all made up as a foundational myth to legitimise the nationhood of Israel. The Kings of Israel before Hezekiah were made up as were the conflicting genealogies of Jesus.
Look, we are talking fairyland when we ascribe unknowable possibilities to fictional characters.
The key to this matter is to find out when and how and where the idea of "heaven" entered the religious consciousness.
Any reward by heavenly existence is certainly not given mention in the OT. To die old and satisfied (at an absurd age) was the ideal for patriarchs.The dream of the Jewish hope, as a landless people, lay in nationalism as a path to plenty, not in a mysterious afterlife.