The Divine Comedy/WMG

Dante is an Ascended Fanboy or Promoted Fanboy.
In Limbo, Dante names a whole bunch of poets and writers of ancient epics who weren't baptised, and thus unable to enter Heaven, yet were awesome enough (to him at least) to be spared the torments of Hell itself. Somewhere in that canto, Dante basically squees in delight at being able to meet his heroes.

This poem is his attempt to join them in literary immortality.

It all makes sense.

The entire series is a Twitter narrative
The character limit is such that Dante is forced to relate his adventures in little paltry couplets tercets.

Dante's convenient little "fainting spells" are ways for him to fake unconsciousness so Virgil won't berate him for not paying attention.

It all makes sense.

That trip through hell wasn't for Dante's benefit.

 * Admittedly, this theory is easier to accept if all you have is the Inferno.

Dante is having a Near Death Experience
His trek through hell, purgatory, and heaven are simply a wildly detailed hallucination of his idea of what the afterlife should be like. This would explain the failures in physics and why he can name the specific people in their representative places. They're where he thinks they should go.
 * Interestingly, several critics think the "Dark Wood" that he finds himself in at the very start of the epic is a metaphor for being suicidally depressed (since the other dark wood in Inferno is inhabited by the souls of the Suicides and the self-destructive in general.)

Dante went to Hell before writing this.
He ended up getting killed, and ended up in Hell. However, being a religious man, he formulated a plan to escape. He eventually ended up in Heaven, where God, impressed by this, gave the man his life back and promised he'd go to Heaven one day if he gave an accurate description of the afterlife. Too bad for Dante Values Dissonance doesn't apply to God.
 * That's not far off, as there's already WMG that he was contemplating suicide; maybe he did commit suicide, but came back to write his tale?