> sufficiently advanced technology might make the construction of probes trivial, so that it has no great significance to its creators

The point is they bothered constructing probes.

My cat isn't constructing space probes. If he up and began doing so this evening, I would be able to conclude certain things about him.

> would be like asking America to account for a discarded Coke can

You're saying you can't conclude anything useful about American culture and civilisation from a discarded Coke can? (As well as the act of casually discarding it.)

> Aliens are completely unknowable, that's the thing most fiction trips up on

Aliens, yes. Aliens who make contact with us, no. The latter is a subset that requires certain attributes and heavily implies others.

> You're saying you can't conclude anything useful about American culture and civilisation from a discarded Coke can? (As well as the act of casually discarding it.)

Not the op, but I would aver that we have a good chance of concluding false things from the alien version of a discarded Coke can.

Given the subject, I would point to the actor who played the lead role in "The Gods Must Be Crazy" (a story about a discarded coke glass bottle), who did not understand the money he was given for the role: https://en.wikipedia.org/wiki/N%C7%83xau_ǂToma

> The point is they bothered constructing probes.

Right, why did somebody make this metal cylinder covered in elaborate symbology and then place it here? Was this place of great importance to them? What were they trying to communicate to me by constructing the cylinder and placing it?

It's just a discarded coke can. You are the one who decided it's required to have great significance. If you haven't read "Roadside Picnic" I suggest at least reading a summary.

>You're saying you can't conclude anything useful about American culture and civilisation from a discarded Coke can? (As well as the act of casually discarding it.)

Could an ant? This is the scale we may be operating on. One of the biggest fallacies with the alien question is that they'd operate on our scale. Let alone "think" as we've observed thinking on earth, but that is another story. Some science fiction has explored this concept based on gravity or metabolism leading to dramatically different scale in either space or time for a species and the implications that brings when meeting a species on a different scale.