Haha you know, speaking of how long Deep Jungle feels like it could take, I didn't have a PS2 memory card until maybe a month after I got my PS2 and Kingdom Hearts (because my cousin told my mom "PS1 memory cards can save PS2 games!" so she didn't grab one with the console). Because of this, for the course of that month I pretty much always made it to Deep Jungle then got stuck or just had to stop before I could finish. The furthest I finally made it before getting a memory card was Traverse Town when you run into Riku after Deep Jungle. The patience we could have as children haha.
But yeah, I miss filling in those blanks as a kid. It'd be cool of the games did more stuff like that, optional little talks if you returned to see someone after a significant event.
I had a similar problem with this, I had no memory card at the time either, but it was so much worse, on top of not being able to save, I also could not get to Merlin's house, you see, at the time I had a bad TV, and this was before HDTVs where main stream, 2004 or 2005, anyway the TV I was using had such a dark screen I could not see where I was going when I got past the door with the fire sign, so until I was able to get a better TV, I couldn't deliver the book to Merlin, and by extension couldn't advance the story, and Destiny Islands was no better, when I had to go to Riku to get the Keyblade, I could not see the bridge, I got lucky a few times with the bridge, that was a miracle, but Merlin, I didn't even have a clue that there was platforming there that I had to jump across, so I was stuck until I got a new tv a few months later.
anyway, my head canon is that Sora is the son of Cloud and Aerith, I mean think about it, Spiky hair in the same style as Cloud's, Blue eyes, same shade as Cloud's, and Brown hair, same as Aerith, at this point, I wouldn't be surprised if it's reveled later that this is true, and Cloud And Aerith sent him to Destiny Islands to keep him safe from sephiroth.