[Jamestown1630]

I think you mean naïveté

Why do you assume that 'they' - if they exist or are anywhere near visiting us - would be hostile?

[Chainmail]

Always assume the worst: if other more advanced forms of life are out there there is better than even chance that they’ll regard us a a disease.

[milemark]

Earth = The Americas in the 15th century.
Aliens = The Europeans.

Vast areas of untapped potential and resources populated by stone age natives.