For me it's the tune rather than anything. But I'm not a singer."
Tune is a contributory factor,but for me it also lyric as a singer the lyric is important.
Dave music and genres are OCCASIONALY LINKED BUT NOT ALWAYS.FOR example the HarryChapin song the shortest story, i heard this sung by richard grainger performed in a folk style, it was very powerful, however we are all going on a summer holiday by cliff richard or lily the pink are typical popgenre that imo have nothing to do with folk music.
then because something uses a folk tune that does not automaticaally mean it is a folk song.
jazz by its defintion has to use some improvisation, so pop songs can become jazz,likewise folk music tunes can become jazz and there will be crossover situations where it could be both, i am sure if charlie parker had played miss mcleods ree[originally a scottish tune]it would have sounded more like modern jazz than a dance tune , so treatment comes into the equation ,for treatment to make miss mcleods reel to use improvisationand still souns folky charlie parker would have to have been steeped in irish folk music ,he was not he was steeped in jazz result it would sound more like jazz .
likewise when a performer is a pop singer and sings a folk song he wil make it sound like a popsong .there are of course grey areas Dusty springfield did a fairly good job of lagan love better than ed shheran singing wild mountain thyme , but as i understand both had some irish roots subsequently they did in the first case fairly well and in the second ok[ although ed should drop the american acct and sing in his natural accent , but can you imagine buddy holly trying to sing adieu sweet lovely nancy.