Has anyone ever checked out Google’s Ngram Word and Phrase Search? It searches out any of the words and phrases you want, to see how often they have shown up in English (or any language you want to check for that matter) literature. When you type in “Jack The Ripper” it shows that it first appeared in books in the English language in 1883, five years before Jack “got to work” in Whitechapel. And when you type in “Jack Ripper” it shows that that particular phase first appeared in 1875, a full 13 years before the Whitechapel Murders. So as far as the Journalist (or possibly Jack himself if you believe like I most likely do, that he (Jack) himself wrote some of the letters) actually concocting the name out of thin air that that IS definitely not the case, it was in use before 1888. Some of it may have had to do with cattle brands or some other kind of animal or livestock brands but most likely the Journalist or Jack had to have read it somewhere (brands or not) in the recent past and liked the moniker and decided to use it for his self.
I think there could be more info to find using Google Ngram relating to this case. Other things like “he ripped her” or “ripping women” (which I haven’t yet checked at this writing) could point to how popular these and other phrases were at the time and how likely it was that the average person might come across them in their regular reading.
This isn’t going to crack the case or anything like that but it could give us a better understanding of the kind of talk at the time to see what people could have been using and what they most likely weren't.