> universe were just so that all of history would happen to lead to you typing that message, and me responding to it, solely by the physical interactions of particles.

You're kinda committing a conjunctive fallacy w/ some anthropic bias. The thing you're not seeing is the infinite similar multiverses that would look indistinguishable to you and you need to remember that the known universe is, very big and the rest of it could be infinite. I don't know how big that number is, but its a lot more complicated than 'this is the only way this could have happened'.