But to answer the question, the danger of AI is uniquely relevant because it is the only danger that may end up being totally out of our control. Nukes, pandemics, climate change, etc. all represent x-risk to various degrees. But we will always be in control of whether they come to fruition. We can pretty much always short circuit any of these processes that is leading to our extinction.
A fully formed AGI, i.e. an autonomous superintelligent agent, represents the potential for a total loss of control. With AGI, there is a point past which we cannot go back.
The differentiating thing here is that blocking hypothetical AI risk is cheap, while mitigating real risks is expensive.
We can work on it in the long term and things like developing safe AI may have more impact on mitigating asteroid risk than working on scaling up existing nuclear, rocket, and observation tech to tackle it.
We don't have any historical record if those peoples had discussions about possible scenarios like this. Where there imaginary guns in their future? What we do have records of is another people group showing up with a massive technological and biological disruption that nearly lead to their complete annihilation.
Btw., the conquistadors relied heavily on exploiting local politics and locals for conquest, it wasn't just some "magic tech" thing, but old fashioned coalition building with enemies of enemies.