For anyone interested, there is an excellent extended article on “Proto-science fiction” in the
Science Fiction Encyclopedia here
http://www.sf-encyclopedia.com/entry/proto_sf
The same source also has an article concerning Lucian:
http://www.sf-encyclopedia.com/entry/lucian
Personally, I think that
The True History is satire using the conventions of imaginative literature in the broad sense.
The Encyclopedia of Fantasy describes the work as “a parody of the travellers’ tales that were already multitudinous in Lucian’s day.”