I am attracted to this picture of language. Whether we are speaking Russian or Polish or Mandarin or English or Esperanto, we all speak subsets of one language, Human. Nobody understands much less speakers all of Human, just as nobody understands all of English. Here is a reason to think this. Among the rules governing speech, we have rules governing whether our utterances are to be interpreted as Russian or Polish or Mandarin or English or Esperanto. In some cases the rule is simply: "If the utterance makes sense as Polish but not as anything else, it's Polish." But sometimes that rule isn't good enough. Sometimes the same sequence of sounds (perhaps with slight differences in pronunciation and accent--but those need not determine the language that is being spoken) will make sense in Polish and in Russian. Typically, but not always, it will have a similar meaning. In those cases, the rule is something more contextual: "If we've just been speaking Polish, and this sounds like Polish, it's Polish." But you can also switch between the languages, as long as you make clear that you're doing so. There are, thus, linguistic rules governing the transition between the languages. This makes me think that all the languages are part of one big language, Human, much as the Olympics are one big game played between nations, containing subgames such as fencing or the pentathlon.
Are computer languages part of Human? I am not sure. They aren't languages primarily for communication between humans. I would say that they are part of Human insofar as they are being used to communicate with other people. But if we met aliens, their language wouldn't be a part of Human, even if it sounded just like Polish and had the same semantics. It would be truly a foreign language.