Sorry, guys, but after a nights sleep I've figured out why it isn't. I was picking out salient features (actually identified by Brian) SPECIFIC to folk songs; very distinct identifying features IMO a good deal more unique to folk songs than having four legs and a tail is to a cat. If I'd just said everything with words and a tune was a folk song, maybe the cat analogy holds. As it is, what I said was more akin to saying, "my cat has pointed ears, says miaow, purrs when content; therefore anything exhibiting these specific features is highly likely to be a cat."

(And no, a cat doesn't necessarily have to have four legs. My aunt had one with only three legs for several years which displayed remarkable agility and often brought mice, birds etc. back to the house)