Those count as blues tunes--early ones, at that--the first two begin by going from the tonic to the dominant and back, something that comes from the last century--(or the second to the last, depending on what century you think this is)

You should be able to get a pretty good rhythm going on a mountain dulcimer, especially if you work on learning to damp the strings--their was an old one string instrument that blues musicians used to play (and make themselves--basically from a broom handle, nails, wire, and a can or pail) I never actually saw a real blues guy play one, but I have heard recordings, and they seem to have been able to get a very compelling sound out of it--suitable for country dances--of course you have to be able to sing real loud to go along with it--

The thing is that you ought to be able to play a couple blue notes--preferably the third and the seventh, because a major scale isn't very bluesy--

I always liked "Make Me a Pallet on your Floor", CC Rider (or Easy Rider) "Goin Down the Road Feelin' Bad" has always seemed like a good candidate for the blues to me, but there are some who disagree--also, if you learn to play the melody to "Shortin' Bread", you will discover that you have plenty of the tricks that you need to play the blues--