So how does Jonah's time inside the fish in anyway "parallel" the dead Jesus laying in his private tomb for three days when Jonah wasn't dead inside the belly of the fish.
The parallel between Jonah's time in the fish and Jesus' time in the tomb is
a typological one, focusing on the miraculous rescue, the three-day duration, and the "descent into the pit," rather than an exact, one-for-one match of physical death.
While some argue Jonah didn't die, others note that he went as far as a human could go without physically dying, experiencing a "descent to the roots of the mountains".
His prayer indicates he felt his life was over: "When my life was ebbing away, I remembered you, Lord" (Jonah 2:7).
The parallel is eschatological: Jonah returned from the "grave" to preach; Jesus returned from the actual grave to preach.
In short: Jonah’s ordeal is a shadow or type that foreshadows the fulfillment in Jesus. Jonah survived the fish; Jesus conquered the grave. Jonah is a sign (a miraculous story), while Jesus is the reality (true resurrection).
Jonah’s Reality: Jonah was thrown into the sea (a place of certain death), swallowed by a fish, and survived for three days in an environment that should have killed him—a "living tomb".
Jesus’ Parallel: Jesus was in the grave (a place of actual death), yet God brought him out, which is the ultimate miraculous deliverance (resurrection).
The point: Jonah is a sign that God can save a person from the ultimate depths