He didn't create it, he just more or less appointed himself maintainer after 1990-ish.
I think it's reasonable to argue that he's revised it so thoroughly away from its original form that he can be considered to have written it. Perhaps it would help to distinguish the Jargon File and TNHD, although the former has for a very long time merely been the latter without the cartoons.
You're not the only one. I give esr a lot of credit for having written the Jargon File at all, because I would not be what I am today had I not encountered it in childhood. But I also give him a lot of blame for writing it in a way that, however satisfactory it must be to his many and multifarious personal prejudices, militates directly against its value in the role he purports to intend that it fill.