I appreciate your recounting of how the retweet came to be, and support your nuanced assertion that things really aren’t invented, per se, because most things already exist. Indeed, email had forwarding since the 80s, and prior to that, chain mail grew up in the 1930s. Clearly propagating a message from one individual to their downstream distribution list has been a behavior of media for some time, and introducing it to Twitter was possibly inevitable, though the form undefined—which is where you come in.
In a similar way, labeling or tagging content in a system too to aid in its discovery is a very old ritual. It was likely to come to Twitter at some point too. I believe that I helped encourage it along based on my observations of the medium, available technology, and working within the constraints of the service, but I wouldn’t claim that tagging was something new. In fact, in my spec I made very clear what my inspirations were, including IRC and Jyri Engeström’s Jaiku microblogging service. I recounted this story in my TEDx talk from last year, lest we forget this history as time marches on!
In general, I appreciate your retelling because the retweet and hashtag are linguistic cousins with a similar development path. For a long time I was reluctant to identify myself as the “inventor of the hashtag” (sounds mildly pompous if you ask me), but in its lead up the its IPO, Twitter tried to assert a trademark on it and after they originally rejected it, I felt compelled to come to its defense. Only then, when I felt it might be taken away from the commons, did I start calling myself its “inventor”.
So the one issue I have with your retelling is your use of the word “appropriate”, which is defined as taking (something) for one’s own use, typically without the owner’s permission. This is what Twitter was trying to do, and was wrong.
I continue to believe that giving credit where credit is due is ethically necessary, and in both our cases I think it is. You didn’t appropriate the retweet any more than I did the hashtag. This may just be a linguistic slip, but clearly as we both know well, words matter.