When people share a life experience in exclusion to the people around them, jargon appears. Old words are commandeered to represent new concepts; new words are created to deal with concepts not approximately represented in the prevailing language. Older language is discarded in favor of newer representations that may be more convenient.
When the Therian community began gathering on the Internet, they brought with them preconceptions from their own life experiences. Therians didn't suddenly and spontaneously appear on AHWW. There were already many people who were noticing significant differences between their own world view and that of people around them. The trigger for the Therian community was simply the realization that there were others that shared that world view. The individuals who gathered on AHWW already had their own personal vocabularies to express, at least within their own minds, their divergent experiences.
AHWW - Alternate Horror: Werewolf was a newsgroup which was founded in 1992 for fans of horror movies. The Alternate Horror newsgroups were decided into genres, AHWW being specifically for fans of Werewolf movies. It was there that Therians first realized that there were others "out there" on a large scale.
Alpha - The Greek alphabet has been used for some time now to designate positions in social hierarchies. It was originally used to describe social organization among school children in the science of sociogrammy. Later it was applied to relational networks among social animals, most prominently wolves. Although some Therians describe their positions among their relations using such terms, it does not seem to be a general usage in the Therian community. Most established Therians tend to avoid animalisic terms to refer to themselves. If that seems paradoxical behavior for animal people, remember that the labels themselves are particularly human things. Nevertheless, some Therians, and among them, some well established Therians prefer to use the Greek alphabet to designate positions in the social groups.