It's interesting that people jump straight from "object we don't understand" to "therefore it must have come from another planet". If I ever suggest to someone

It's interesting that people jump straight from "object we don't understand" to "therefore it must have come from another planet". If I ever suggest to someone that it could be, for example, an animal that no one has ever seen before, atmospheric phenomena we've never observed before, experimental aircraft from another country, experimental aircraft from the US, disinformation campaign by the US military for some yet unknown reason, lone scientist's experimental drone, simultaneous hack of all pilots systems, etc, I'm usually met with "don't be silly, those are impossible". Well, why isn't "alien spaceship from another planet" also impossible? Why is that more likely than the other explanations?