I don't think I entirely understand the question here. There are significant cultural similarities between North West Germany and Denmark in general and Jutland in particular. There are significant cultural similarities between the pair of them and England. It also happens that the political centre of Denmark eventually became Copenhagen (so open to Swedish influences and, of course, the function capital of both during the Kalmar Union period), that there were always other cultural influences in England, and that the political centre of German, though always mobile, was last in the North West of the country during the transition between the Early and High Middle Ages.
I guess I also don't really know how to rephrase it, haha. I am not doubting that Danes and Northwest Germans have similarities (as nearly all bordering ethnic groups do), but the fact is they both trace their ethnic/linguistic ancestry back to groups that diverged quite a long time ago (North Germanic and West Germanic tribes). I guess it has never made sense to me that (A) "Denmark" developed a North Germanic language rather than a West Germanic one and/or (B) why Jutland itself developed as part of what would become "Denmark" rather than what would become "Germany." To simplify or phrase another way, why did Denmark develop a culture such that the detached Justland Peninsula would today be considered part of "Scandinavia" despite not being on the Scandinavian Peninsula and functionally/physically just an extension of the land of Northern Germany. To me it seems akin to (from a strictly geographical comparison, as I know the histories are obviously not comparable) Long Island developing a culture closer to Rhode Island/Connecticut than to Brooklyn.
Because Copenhagen is more accessible to Jutland than any major German cultural center,
