I love anything by Rory Gallagher, his songs aren't too difficult...if you ignore the solos lol
Manchester United Est. 1878

Do you DIG?

Cos I DIG.
I think that Give me one reason by Tracy Chapman is really easy, but I'm not so sure if it is blues...
I'm not really prominent in blues expertise but you could try:

Bring It On Home - Led Zeppelin (Especially the intro)
La Grange - ZZ Top
Bad to the Bone - George Thorogood
The Jack - AC/DC

That is for a more rock-blues hybrid. I really don't really know any easy, soulful, classic blues songs. But definitely look at Bring it on Home. The intro to that song (and The Jack) is the shuffle riff with few variations which is used a lot in blues. Also look into ZZ top for some fairly simple riffs.

You should research into the 12 bar blues as well and the Minor/Major Pentatonic scale as your abilities progress.