So, I was poking around in the sound.jar extract folder, and I took a look in the '010-Music-Incidental' folder, and it contains all the songs we know and love from Wurm today, as well as some extra super-intense ones that sound like they are triggered during PvP(Could someone confirm?).
The I took a look at '009-Music-Specific' folder. I had been looking for that sweet riff that plays sometimes for no reason so I could save it and maybe use it in a dumb edit, but what I found amazed me: The entire(?) collection of original Wurm music by @Gurubearand his band, 21st Century Blues, Including classic hits like 'The Raven', 'Little Miss Jane', 'Village Work song', and of course, 'Wurm is Waiting', as well as a few dozen background tracks of various themes. I have only heard a few of these tracks in-game, and few on the 21st Century Blues YouTube channel, but there are many more that probably nobody has heard for years.
Another thing to mention is that the three Kingdom Anthems are there as well(which I think sound awesome!), and also the very last track aside from the achievement sound effects is Gurubear "wishing all Wurmians a merry Christmas, from Rolf and the entire team!", which I assume was used in a Christmas event or message way back when.
A bunch of them seem to fit some sort of theme, but it's hard to tell what. Any older players with a keen ear for music and a good memory, please share what you think the songs were for/from!
If you want to have a listen to these, all you need is a tool that can extract .jar Java Archives, and to extract the sounds.jar file in /yourwurmfolder/packs/. All of the sound files have ambiguous names, so you'll have to look through them all to find ones that are proper songs, but I think it's definitely a worthwhile thing to do while mining out an iron vein.