The current images of hell certainly find their seeds in the New Testament. The problem with citing the Old Testament/Tanakh, however, is that you are reading later translations that were made by Christians, a point that stongly influenced the words chosen for “hell.” In the Hebrew bible the references that are translated as “hell” in English language bibles are usually either Sheol or Gehenna. Sheol was the dank afterworld to which all souls were consigned, regardless of the quality of life one had led. It was very close in concept to that of the Greek Hades. Gehenna was a valley south of Jerusalem which had been the site of human sacrifices to pagan gods and was later used as a trash heap. It was a place of smoldering fires and stench and the bodies of rebels were tossed there rather than being given a decent burial on a couple of occasions. Jeremiah and Isaish each invoked the image of Gehenna as a place where those who were so sinful as to be without redeeming valley were “tossed away” into the fires.
Later, when the Jewish people began exploring concepts of reward and punishment in the afterlife (whether borrowed from Zoroastrianism or taken from ideas of the time which were, themselves either adopted by or donated by Zoroastrianism), the name Gehenna was applied to the place of punishment and the image of the fires in that place were used to create the imagery. A number of intertestamental works (books written after the last Hebrew book and before the New Testament that were never adopted as Scripture by either Christians or Jews) created an extensive theology and imagery regarding the place of punishment that has now been adopted (with some revisions) by most Christian groups. These books included Assumption of Moses and Apocaplypse of Baruch, and in 3 Esdras. (3 Esdras is a name given to a Greek copy of Chronicles, Ezra, and Nehemiah that includes additional stories and verses not found in the Hebrew originals.)
Pointing to a reference to the word “hell” in an English language Old Testament simply does not mean what it appears.