what are charlatans ?

A charlatan is a fraud or a person who pretends or claims to have more knowledge or skill than he or she possesses. I don't know if all the characters are charlatans but Welles tells us he was making the whole thing up at the end of the story. He admits the entire story of Kodar, her grandfather, and Picasso was made up. He apologizes, quotes Picasso's statement that art is a lie that makes us see the truth, and bids the audience good night.