I would not say it came from nothing, although it certainly could look that way.

There are random variables popping up so it could come from where they do. This is a complex subject and I have already written a few posts about this.

But even if you think that information vanishes after a person dies, it always come back in some other form, so it's not permanent.

Sort of like how you you get a random number with the probability of 0.00000000000000000001%, it's a very rare event. But eventually it will repeat itself.

So any thought or information that arises in somebody's mind, will eventually arise in somebody elses mind in the distant future.

I think that is how nature works basically.