>Looking back historically, many of the European powers of the 1500s-1800s were literally millennia ahead of the people they colonised in terms of technological prowess.

I don't think this is true. India was colonized, and it had very comparable technology - perhaps 50 or 100 years behind. There are cases of very primative people being colonised of course, but often the capabilities of other civilisations are minimised in our history - for example north american natives are seen as hunter gatherers whereas there was extensive farming and land exploitation in many places in the USA - along with pottery and settled living.

OK, perhaps I could have been a little bit more precise with my language, given this is HN, but the overall point still stands.

We have hands-on experience as a species with technologically primitive societies being discovered by technologically advanced societies and going on to influence language and philosophy.

Given this, I don't think it's a given that an advanced alien race would look at us as not worth their time.

European colonizers needed resources (gold, food) and territory. But that's because we have limited supply here on Earth. But in outer space, both are abundant, e.g. it's much easier to mine water or gold out of comets and asteroids, than lifting it up from a planet. If aliens are so advanced, it literally costs nothing to them to choose any other planes on the sky.