Within the Old Testament, through intertestamental literature and even in the New Testament, it is possible to discern an evolution of thoughts concerning She’ol/Hades. If we take into account this evolution, the main biblical pattern of the immediate afterlife is that there is a temporary place for dead people like a "waiting room", without a definite and precise description of the form of existence by which dead people are actually still existing and alive. We only know that it concerns the soul or the heart without being clear.
In this pattern, She’ol/Hades is divided in two places that can be called Paradise and Gehenna. The first one is the place to be, with the patriarchs1. The second one is a place of torments2 often associated with fire (and other bad things)3 that may well be a metaphor of torments associated with understanding the spiritual irreversible consequences of earthly choices.
In Jesus mind She’ol/Hades is not any more this place where people are silent in a kind of lethargy, living like shadows. Even more surprising : Jesus also says in Matthew 12,404
40For as Jonah was in the belly of the huge fish three days and three nights, so the Son of Man will be in the heart of the earth three days and three nights
Himself had to go in the underworld as an intermediary state preceding His resurrection.
Note
1 At this level of our reasoning, we should only mention Abraham. But see in following sections the commentary about Luke 20,27-38.
2 Greek βάσανος.