Who were the first known inhabitants of united kingdom?

The first known inhabitants of the United Kingdom were the Celts, who arrived in Britain around 600 BC from mainland Europe. The Celts were a diverse group of people with their own languages and cultures, but they shared a common heritage and identity. They built hillforts, roundhouses, and other structures, and they practiced a form of polytheism. The Celts were also skilled metalworkers, and they produced a wide variety of artifacts, including jewelry, weapons, and tools.