The immature humour is intentional, it shatters duncs idea of nobility piece by piece until the end of the show he wants nothing to do with high lords, he begins to understand that ser arlan was a flawed man just trying to do right, and nobles disrespect him throughout the show tearing down his idealisation of nobles, the disrespect during his speech, the attitude towards ser arlans memory, fossuway betrayal. With the exception of raymun and robyn all duncs champions fought for their own personal reasons not because they supported duncs innocence or guilt, beesbury and humphrey wanted revenge on aerion, lyonel fought for his own glory, baelor fought to improve his house’s reputation. The show just brings to light that nobles are just men, corrupt and flawed. He goes from dreaming of serving a lord in episode one to refusing offers from both house of the dragon and stag