Even the righteous said/believed they were going to Sheol.
I believe that one of the reasons that the idea was developed that Sheol might include a place for the righteous is because it shows up in the OT was when Jacob said that if Benjamin were killed it would bring down his grey hairs to Sheol.
This was interpreted by some as the same as the grave. But others developed the idea of a compartments in Sheol for the righteous and the wicked. However, most likely Jacob is saying that he must have done something to deserve the place of the wicked dead if he lost both his sons and was referencing the place of the wicked dead and not just the grave.
In other words I don't think Jacob understood Sheol to be the grave nor did Jacob intend to communicate that he was going to go to the righteous compartment in Sheol. He was probably venting that he was going to "hell" because why else would he lose his favorite wife and his two favorite sons in such tragic ways? He must be cursed by God.
There was a belief that Sheol was divided by compartments for the wicked and the righteous divided by a handbreadth but these were teachings of select schools of rabbis with no biblical basis. They used to make up many things that were not in the bible.
My point is "what can we know from researching the word in the OT alone?"
I got this from reading about this word Sheol in the past.
I was confused by all these words and how people were teaching so many different things about Sheol, Hades, Gehenna, Tartarus, etc..
I could be wrong. But so far I am leaning toward Sheol being the same as how most of us understand "Hell". A place of punishment for the wicked dead. I am not on board with the rabbinical teachings about Sheol. As I am usually not on board with most rabbinical teachings that Christians are falling for by watching YouTube videos today.
And following the KJV scholars on communicating
Hell as that word that most English speakers understand I think we are probably communicating the intended message when we use that word.
Proverbs 15:24 “The way of life
is above to the wise, that he may depart from hell beneath.”
This is probably one of the best verses in the OT on the subject.
It was the scriptural understanding on the subject that the OT communicated and they really were not given a lot but enough to warn them that there was a place of torment awaiting the wicked dead. This is why Jesus said in his parable that those 5 brothers of the rich man could read Moses and the Prophets to be warned about "this place of torment."
I think if one reads all of the references in Moses and the Prophets on this place they come away with a scriptural understanding that it is a place of torment for the wicked, and they don't get the idea that it is a place for both the wicked and the righteous. This idea is presented by other teachings outside of the scriptures such as Rabbinical writings.
That is my understanding so far, but I am still reading and learning.