Other people here have shared ideas about handling narrative/lore concerns so I'll take a different approach.

The first 40-60 minutes of the game should be a series of cutscene montages and solo combat instances. The cutscenes briefly show the story highlights of each expansion, interspersed with combat instances to teach both job skills and battle mechanics. Think of it like a cinematic Hall of the Novice.

The solo instances can play with the chronology of events a little bit to speed things along while communicating a feeling of rising danger and stakes. For example, after a cutscene montages that introduces the ARR primals, you play a solo instance where you fight Ifrit, then Titan, then Garuda. In later instances, you might fight various lightwardens in sequence, then Vauthry.

This would give new players the feel of the game while communicating the basics of main characters and events without them needing to have an extensive understanding.