I have no qualms with the origins of AG tech on Earth as shown in the various shows. I don't see any contradiction there at all.
According to Babylon 5
the Minbari used aritificial gravity before Earth even had the faintest idea how to accomplish such a feat.
(sorry, couldn't resist temptation).
Interestingly, the TOS creators were very aware of the necessity of artificial gravity. The Writer's Guide explicitly mentioned life-support and
artificial gravity (access to which, IMHO, restricted to "Environmental Engineering Personnel Only"). And in the background chatter, after a bumpy ride, one of the sections to always report first was the "AG Section".
Unfortunately and eventually artificial gravity was taken as "granted" and I consider the depiction of AG in "Space Seed" as one of the major screw ups. In his original production sketches, Matt Jefferies depicted the modules of the Botany Bay
as cargo containers. Had one full 360° segment stayed in place
, it could have been rationalized as a centrifuge simulating artificial gravity. Too bad that didn't happen...