Are you so foolish that you believe that one out-of-context passage proves your assertion? Where does this passage says Gehenna was "a place where dead people were, dead bodies. To be cast into Gehenna means to be dead?"
It says the dead are there right here:
"for they will bury the dead in Topheth until there is no more room. Then the carcasses of this people will become food for the birds of the air and the beasts of the earth."
Topheth is Gehenna.
I am not so foolish that I think
one passage proves my assertion. The full context of the Bible indicates that people die and go to the grave. This passage shows that the Jews thought of Gehenna as a place of the dead. See where it says
they will bury the dead. No one is burying ghosts! See where it says
carcasses? These are not living carcasses. These are dead carcasses. There are so many that there is not enough room to bury them all. The late comers are piled on top. The birds and beasts (and the worms!) come and eat them.
You know, not every bible passage that disagrees with your established position is "out-of-context".
Some Jews of the period believed that ghostly spirits hang around the underworld. That is to be expected after Alexander conquered the middle east and brought greek ideas in. That does not mean that they are right about "the spirit world". I've read your links and they are split in half. Half seem to indicate a shadow life of death in the underworld and half show that the dead are fully dead waiting for resurrection. There wasn't a consensus back then, either. You wouldn't expect to find only one position in a land full of Jews, Greeks, and Romans, also influenced by Persians and Egyptians. Even among just the Jews there were factions. There were Pharisees, Saducees, Essenes, Samaritans, and Zealots and they all had different ideas.
I believe God inspired the Bible, and the truth is recorded there. From all of the ideas of the time, God selected the truth to be written in the Bible.