These are not Norse runes. This is quite simple really in the end, as the most famous Norse runic inscriptions are significantly younger than this Basque text, by about 5 centuries, and come from hundreds of miles away. The Younger Futhark alphabet, the runic alphabet of the Norse people in the Viking Age, only started to be used starting in the 9th century AD, coming out of the older tradition of Elder Futhark runes which stretch back several centuries older. However this find is not of Elder Futhark, or Younger. Quite simply because if it was we'd be able to read it! Futhark as an alphabet, and the languages the alphabet was used to depict, are reasonably well understood by linguists and have been for centuries. And while the characters on this find are superficially similar to the runes of Germanic peoples, they are ultimately coming from a different, and distinct, language tradition. There may have been similarities in how the letters were transmitted, but they ultimately are not the same language or alphabet.

Most runic alphabets, the Elder and Younger Futhark included, are derived ultimately from Italian alphabets that were proliferating around the turn of the millennium. This is something of the dirty secret behind most runes, they were not endemic creations of the peoples who used them, but were rather an adaptation of existing alphabets to suit the languages of Germania and other parts of the world. The runic alphabets had to change as they met new languages and that is how we ended up with several different variants of the runic alphabet, the English, Scandinavia, Gothic, and so on variations though all still originated with an ultimately Italian derived script. The runes of the various Germanic peoples changed and were gained and lost over time before arriving at the "final" stage of Medieval Runes following the close of the Viking Age in the 11-12th centuries.

What we see here is still preliminary and I'm sure there will be a good bit of scholarly ink that is spilled over this find in the coming months and years, but there are some thing that we can say for certain. It is possible a similar situation was at work in Hispania as well, with literacy in a runic alphabet preceding Latin literacy, but I will leave discussion of the specifics of Hispanian languages and alphabets to someone a little more familiar with the topic.