Just a few more thoughts on this.

Every song or tune must have been composed by some individual or group of people, however long ago it was. The authorship of many old songs/tunes is unknown simply because nobody bothered to record the authorship for future generations. At the time a song was composed, people hearing it for the first time would know it was (say) a "Joe Bloggs the Fiddler" tune or a "Fred Smith song". The fact that we have lost this information doesn't make it any less true that each of those songs and tunes were composed by a specific person.

There are plenty of songs and tunes where the author is known, but they are nevertheless out of copyright. Are these songs be denied being called "traditional", just because we know the author's identity? If two songs were written in (say) 1820, and the authorship one one of them is known to be "Fred Bloggs", and the other's authorship has been lost, is only the latter allowed to be called "traditional", even though they might be very similar in style?

One day in the distant future (assuming the survival of the human race), the songs being written today might become known as "traditional", if somehow their authorship is lost (seems unlikely but who can tell?).

If a song or tune is written today in a "traditional" style, why can't we call it "traditional", anticipating that it will become so in years to come? Why do we have to wait?

Any thoughts folks?