“This would be unknown, except for the story re-told in the movie, “Jaws””.
You’re wrong.
You’re both right.
When John Milieus a history/military buff read a quote from a surviving crew member and dramatized it, gave the Indianapolis story international legs. Almost everyone on the planet soon knew the story via that scene.
But historians and military buffs had and would have known the story without seeing ‘Jaws’.