So am I correct these are people who predated the Celtic waves into the British Isles?
Were they Picts?
Or wideranging North Germanics straying from Norway, etc.?
Or something else?
This was simply a settlement created by the descendants of people who'd holed up in the Western Refugia South of the Pyranees in Spain.
In fact, at this time the people who became the Celts were still pretty much on the Continent and hadn't reached Britain, but there were already people there. The Germans do not achieve a separate identity until they rebel against their Celtic overlords along the Danube. That's about 1000 BC.
Here's something for you to keep in mind. Ancient peoples can be identified by culture (pots, designs, etc.), DNA (taken from bone fragments), or language.
You get back a few thousand years everybody is a stone ager ~ or Paleolithic hunter/gatherer who makes his arrowheads and other stone tools in a certain pattern.
Then a little further toward our time they are making baskets and pottery that manage to leave behind impressions or shards. Again, that's culture.
Finally, we come to the age of writing ~ which starts in Sumer and spreads rapidly ~ and that gives us history and language.
This village in the Orkneys is pretty old ~ but not as old as some in Ukraine where people settled who'd been protected from the ice in yet another refugia.
There are places even older than those in the Middle East.
What is exciting here is that civilization in Britain appears to have been an indigenous product and wasn't shipped in by foreigners.
The Book of Invasions records (I think, if memory serves, other disclaimers) four waves of settlement of the British Isles, each one named and characterized by some activity or burial practice, or etc. The Celts hit Europe prior to 600 BC (including Galatia, now part of Turkey, and probably best known for Paul’s Letter to the Galatians), and had covered most of the British Isles (including Irelend) by 500 BC. Other places of settlement included Iberia, northern Italy, and other spots.
The Celts in Britain are (or at least used to be) classified by language into P-Celts and Q-Celts; the Irish and Scots are Q, and the Cornish, Welsh, and perhaps the earlier Celtic wave in Ireland P-Celts. The most obvious and frequent example of this is Mac (son of) in Q-Celtic is Mab (or Ap) in Wales. The last native speakers of Cornish died out about a century ago. The last of the Gaelic-only speakers in Ireland are still in the process of dying out, but it’s close.
The Celts moved out of Central Asia (not Germany as is sometimes claimed) as a consequence of their population growth hitting a wall, probably due to natural climate change, the same driving force that pushed IndoEuropean language speakers into Europe in the first place from the same spot. It also pushed IndoEuropean speakers into Iran and the Middle East, India, and into the east.
The upshot is, the Celts were a later follow-on wave of IndoEuropean settlement / invasion of Europe, which continued into the Middle Ages. And speakers of non-IndoEuropean languages followed the same route — the steppes — from east to west (and from west to east) throughout Greek and Roman times, and into the Middle Ages. The cork didn’t get stuck in that bottle until Ivan the Terrible defeated the Muzzie states that had been pushing them around, and put the Russian Empire together. Prior to that time, the Slavs (also IndoEuropean speakers) were part of that settlement / invasion of Europe.
Stonehenge antedates the Q-Celts in Britain, and since there are good dates for the stages of its construction, and good dates for the pre-Q-Celtic cultures (which correspond reasonably well with the descriptions in the Book of Invasions), it remains likely that the P-Celts’ arrival also is subsequent to the construction of Stonehenge — and therefore of this complex in the Orkneys.