Thoughts about diversifying

So I have been investing for a couple of years now, mostly in index funds, ETFs and some individual stocks. When I started, I didn’t know what I was doing at all so I was dumping all of my cash into indexes and etfs that basically contained the same stocks, and what’s worse I bought some individual stocks that I already basically owned. Now I’m overexposed to AI and also the American economy despite being European. I know that I shouldn’t have been investing without knowing anything about anythi