I just replayed Secret of Mana on an original SNES co-op with my spouse and it was truly awesome. Many people who have played a lot of JRPGs still haven't played it.
And I'll second the Octopath Traveler recommendation!
(spoiler alert) there is an undead boss in Final Fantasy 8 who is incredibly hard but can be killed using a "Phoenix down" (which is an item that revives dead players). As a kid, I got a real kick out of it.
Also let's not forget the dawn of MMOs, with UO and then the revolutionary EverQuest in '99.