Gentoo bans AI-created contributions

Just to throw another wrinkle into this discussion, I believe that in "ich bin arbeitend", the "arbeitend" would be a predicative expression, which is different both from an adverb and from a way of expressing what English would do with present continuous. It simply describes a state that you are in. For a better discussion, see https://en.wikipedia.org/wiki/Predicative_expression

I understand why it is tempting to say that the present participle is used to form a present continuous. That would feel very natural to an English speaker who is familiar with Latin. And it feels almost but not quite as if German should do the same. In fact, I wouldn't be surprised if some regional German dialects did this. There is a lot of cross pollination between all of these languages, but in the process grammatical concepts get repurposed and subtly change.