Just common sense, which the Zandalari, of all troll tribes, have never lacked for.
Zandalar has been an island for over ten thousand years. Sure, it was originally built on a mountain. Now, it’s an island. You don’t think ten thousand years of being an island is enough time for them to go, “You know, we should probably build a fleet. Lots of dangerous nonsense in and on the ocean.”
Also, the nation wasn’t founded on an island. It was founded on land-blocked mountains. The Zandalari were never a sea-faring people.
Sure, just ignore the time the Zandalari set sail to fight the Soulflayer, when they set sail to record the downfall of the Drakkari Empire, when they started exploring islands after the Sundering, when they set sail after the Cataclysm…
Zandalar will ultimately be more important than KT simply because it’s the mecca of trolldom and blessed by more wild gods/loa than even the Night elves roll with.
Gazlowe spent enough time in the Zandalari docks, shipwrights might have picked up a few tips about efficient industry from him and started pumping out ships. Arsenal of Democracy Councildom, baby.
In what reality sense? I fail to understand how any individual could be more important than entire race. Jaina is not a culture unto herself. She is not a multitude of stories large and small. She is not a self-contained dynasty, faith, and court of politics.
Perhaps as a story-telling element she has more significance than the Zandalari, but that’s only determined by how convenient she is or isn’t for a given narrative, compared to the same criteria for the Zandalari.
Jaina’s a major lore character by all accounts, but she’s not playable race levels of important.