Dear Little Hawk, Dylan, "that little scrawny shnook" as you described him, was but a pin prick to Dominic Behan's thick hide. Behan's writings were about the wrongs inflicted on men and women by society but especially concerning Ireland, his country. He wrote many songs other than the Patriot Game .. Come out Ye Black and Tans .. for instance and Connolly was There .. the originality of the melodies was not important but the lyrics were. I knew both Dylan and Behan and can only say that Dylan's chip was much bigger than Behan's. Dominic was established and Bob had to make his way when I knew him so just be happy than Bob got his fame and glory which Dominic already had. The message regarding plagiarism is that one can use traditional tunes, which many of us song writers do, but write your own songs.
I don't really want to continue this discussion which won't have a satisfactory end for most people as it parallels threads about MacColl .. there are those for and those against and never the twain shall meet. Just take a deep breath and enjoy the music.