Jonah was a prophet of God who was working the beat in the mid 8th century BC. Unlike some of the other prophets at the tail end of the Old Testament, Jonah is speaking during a time of relative peace in Israel as the Assyrian empire hit a conquering lull and the kings of Israel, Jeroboam II and his father Jehoash before him, had reclaimed most of the land they lost to the Assyrians in the century prior.
To the question of whether we should consider this story, and some of its more fantastic events, as literal history, we should note that in Matthew 12 Jesus seems to consider the contents of the story as actual history. Thus, with little further consideration outside of this fact, we should treat it as something that really occurred while understanding that it is written to include things like metaphor, such as Jonah’s prayer in chapter 2 where he claims to be rescued from Sheol. He wasn’t literally in the “belly of Sheol”, it’s an image that speaks accurately to his circumstances without being a literal description of them.
In general, Jonah is a pretty quick and relatively easy read. However, slow down and keep an eye out for details as the story is well constructed and specifically worded. Watch for repeated phrases and who they come from as well as comparisons between different people or groups of people within the story.