I was re-watching Chamber of Secrets and when Harry is destroying Tom Riddle’s diary
Harry had no idea that the diary was a horcrux. He also had no idea that Basilisk fangs could destroy horcruxes. Or even that the fang would do any damage at all.
He was literally just doing it because he was pissed at Tom. Harry Potter destroyed a horcrux at 12 years old by sheer dumb luck.
And that’s basically a summary of the entire Harry Potter series.