As I understand it, the earleist settlers in the British Isles moved in after the last period of glaciation, but didn't leave us much evidence of their racial or language characteristics. Paleolithic hunters and gatherers, maybe 8000 BC. That was when the British Isles were still connected to continental Europe (and to each other) by a land bridge, before the glacial melt made the sea level rise, turning the area into islands.
Then the Celts came in, pushed west by the Roman conquest of France (Gallic Wars) (1st century BC). Eventually the Romans pushed right into what's now England ( 1st century AD), and the islands' inhabitants were still, loosely, Celtic, and spoke the Breton, Welsh and related languages.
The Romans withdrew in the 4th century AD, which cleared the way for barbarian raids from the North and East.
They were invaded by the Angles and Saxons in the 5th century , and gradually evolved the Anglo-Saxon language, which is West Germanic. The Celts (Gaelic) were pushed even further to the margins, north to Scotland and west to Wales and Ireland.
Then in the 11th century Anflo-Saxon Britain was invaded and settled by the Normans from France.
So it was Paleolithics (unknown race and language) ==> Celts (Gaelic) ==> Romans (Latin) ==> Angles and Saxons (Germanic)==> Normans (French)
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Those “Paleolithics” left behind inscriptions on the northern most shores rocks in ‘paleo-Hebrew,’ a pictographic language that may have been what all of the people used, pre-Babylon.