Theese are NOT viking runes. They are an older Rune alphabet, from around year 500 and earlier. They are called the elder futhark. The viking Rune alphabets have usually only 16 runes and there are several different alphabets from that time.
The Ouroboros or Uroborus often represents self-reflexivity or cyclicality, especially in the sense of something constantly re-creating itself, the eternal return, and other things perceived as cycles that begin anew as soon as they end (compare Phoenix).
Ragnar Lodbrok from the Viking TV Show with a raven on his shoulder. According to Viking mythology, Odin would often appear as a raven. Ragnar Lodbrok claimed to be descended from Odin and many Vikings believed this.