This is the core of cognitive behavioral therapy.

Your thoughts don’t come out of nowhere. They are based on your own set of beliefs, usually shaped by experiences.

Change your beliefs and you can change your thoughts.

Yes, the above approach is exactly what I advocate we should avoid.

"you are an empty vessel and they arrive in your mind by magic"

Whatever: https://en.wikipedia.org/wiki/Analysis_paralysis

But you're right! All our truths were invented by someone else(s), down to the language we use to write these replies.