You're talking semantics here which has nothing to do with music.

Traditional, means within, or coming from, a tradition. So ANY music HAS to be traditional 'cos no music is written in a vacuum. "Happy birthday to you" is obviously traditional and is still in copyright.
"Lincolnshire Poacher" is out of copyright but is also traditional.

Copyright is held until 70 years after the author's death. Again it has nothing to do with music.