[s1mplicissimus]

Air currents are highly complex and almost impossible to model in detail, that does not mean that they are not the outcome of conditions that preceded them (regardless of whether we know the formula).

So why were the air currents slightly different? Oh I guess because the surrounding weather must have been slightly different. And how did that happen? Because the surrounding climate was different. And how that? Because earths development facilitated that different climate. Maybe the moon was bigger? Earths mass smaller? Well that's a big ask for a historical event we know happened on our known earth surrounded by our known moon.

[kragen]

No, it wasn't because the surrounding weather was slightly different. The surrounding weather was exactly the same. The air currents were slightly different because a warm rock in Karnataka thermally emitted a photon 13 years earlier that it didn't emit on our timeline. (This happens, as far as we know, completely at random, without any cause; cf. https://en.wikipedia.org/wiki/Quantum_indeterminacy.) That was enough to cause the global atmospheric system to diverge enough that the mosquito stung someone else.

The findings of chaos theory are counterintuitive, but they are absolutely fundamental to how our universe works.