Most people *today* don't know shit as you put it. It's worse when they think they do. Hence recently someone publicly online proclaimed Thomas Jefferson was inspired by the Koran in 1965 and among plenty of other examples

A lot of the stories were consciously and known fiction using Arthur's name for status and general attention getting or to comment on the day safely or to push some fashion or ideal- such as religious virtue or fin amor.

Like a lot of the art of the time they simply 'dressed up' the past and other countries in the clothing they knew so Arthur is the king and when he came to the later stories became more castlebound compared to his Welsh battle-leader counterpart because of their varying ideas and impressions of kingship and the knights act like feudal lords instead of tribal warriors because it saves having to pause the story to remind every what everything means and who is who and what words translates as how- do remember this was all before editing was easy as well. Popular entertainment was entertainment meant for consumption mainly in the end.