Historically, there is no proof that King Arthur existed and Camelot was not presented as historical, but as a fictional location.
The oldest known works about King Arthur makes no orientation to Camelot by name. Camelot is first cited openly in the romance called Lancelot written by the French poet Chretien de Troyes.
The legend traces it somewhere in Britain and sometimes links it with real cities: Winchester, Cornwall, Somerset though more usually its specific location is not revealed.
Religion, legends, and literature alike are replete with various conceptions of ethereal or terrestrial paradises or places with romantic flair. See examples of ideal locales, including their names, their origins, and their definitions at Daily Writing Tips.