The correct answer is ‘no-one’ of course, but I would say Alan Horne has a good claim. Postcard Records were arguably the first indie label in the early eighties to start making music that was definitely nothing to do with either punk or post-punk in either its sound or aesthetic.
Most of what anyone would call ‘indie’ since has links to the records Postcard released by Orange Juice, Aztec Camera, Josef K and The Go-Betweens between 1980 and 1981.
To be fair, Flying Nun followed very closely after, although they didn’t have quite as consistent a vision as Postcard.