A lot of people take credit for NWO. Greg Gagne is another one who took credit for all of that shit as well.
Bischoff and Dillon went to a NJPW show during the UWFI angle and decided to use the angle to introduce Hall and Nash. The name came from Larry, but all the other shit like "paid advertisement" was Nash and Hall. Nash in particular spoke a lot about how WCW tried to sell shirts and shit in stands, and Nash got pissed because it didn't make sense, so they decided to hire a bunch of girls to sell them from the trunk of cars (so it looks like bootlegs).
A lot of people had something to do with the NWO, but ultimately, I think Bischoff, Nash and Hall are probably the ones that came up with most of the ideas. Even Hogan's promos (Watch the first couple of promos, where Hogan can't help himself but go into his 80s cadence) started changing because Nash and Hall told him it doesn't make sense. Part of the reason they did Paid Advertisement pre-tapes was so they can monitor Hogan-- who did eventually get it.
Looking back, I kind of miss the 96 NWO. It felt really dangerous. Nash, Hall and Hogan with Dibiase. I like Bischoff, but his joining never made sense, even though he was a great heel. Then, they get Giant. I feel like the angle started falling apart around 97, when Hogan stopped showing up as much (so Spring 97), they even did the first "NWO split" story here.