>I have always been under the impression that the only reason children learn languages faster than adults is because they don’t worry so much about how they would be perceived if they said the wrong thing, pronounced something wrongly etc.

To piggyback on this, as someone learning a language as an adult, one thing that frustrated me the most was the inverse of the phenomenon you described - adults trying to be too polite and not correcting me when I made some mistakes, as long as they could understand what I meant. As soon as I had made close friends and made it explicitly clear to them, that I would really appreciate them pointing out my mistakes, that's when my biggest learning leaps occurred.