The Han script was really a unified VM bytecode and serialization format, not a language spec.

The fangyans are various languages compiles to it.

The Chinese standardized its written form very early, and is the only "language" survived today without an alphabet, many native speakers learn "Chinese" as the text rather than a spoken tone. Even Cantonese and Hakka are really a family of mutually unintelligible dialects clustered by geographic proximity.