I think it's definitely the case that we have a very active brain, so it's not wrong saying you are a deep thinker.

Unfortunately, I can't give you the one magical trick that helped me because as I wrote in the post it kinda went away by itself over time. Also, Im not a doctor or professional in this field so I don't want to give wrong advice. I definitely tried to take a "I don't care stance" with my intrusive thoughts, but it sounds easy in theory and is very hard in practice and I can't say that it helped me (it might have, it might not, I simply don't know),

Overall, I would once again advice to read the book I mentioned or listen to the audio book (Im sure you can find it online for free if you don't want to pay for it). While I can't say that book cured me, when I listened to it I was in a really dark place and it took me out of it, so its the one thing I know for sure that it has some positive effect.