Hey, you’re the same age as me! I was also 14 when the CS wrapped (God, I feel old…).
I thought the mastermind would either be Norman or perhaps a resurrected Ned Leeds (this was before Hobgoblin Lives retconned the original HG to be Kingsley). I was sure Gaunt was Harry, and remember being disappointed that it was some villain named Mendel Stromm I had never heard of before. As for the Norman revelation… I didn’t even have the internet at home in 1996. I could use it occasionally at school but wasn’t really aware of fandom sites or message boards yet. So the comics did reveal it to me, but being a kid with only allowance money, I could only afford a few issues a month and had to wait until PP:SM#75 was out to go to the comic store (I would get ASM #418 as a back issue a month or two later), so seeing him on that awesome cover is how it was revealed to me.
I know it was controversial and plenty of people hated it (with good reason), but to my teenage self the revelation of Norman was one of the only mysteries that lived up to the hype. I wasn’t happy about Ben dying (and not being in costume), but I thought everything related to Peter and Norman’s battle in that issue was great. I still think it’s one of Mackie’s best issues (even though I get the sense it probably had some contributions from other writers). The only other Spidey mystery that I think might’ve lived up to the hype was Venom; first the revelation Peter’s suit was alive, and then the revelation that it was Venom who had been trying to kill Peter for months without setting his spider sense at the time. But I can’t say for sure how satisfying it was for fans at the time as I wasn’t yet reading the comics. But I can imagine it was cool.