Ganymede's an extreme example as it's quite literally next door, and we still have absolutely no idea what swims in its 60-mile-deep oceans, save to say that they're not shooting lasers through the ice or launching satellites. Do you know from what distance we'd be able to detect an Earthlike planet with extraterrestrials who are at a current-Earth tech level?
> none of them talking about advanced extraterrestrial life are built upon any known scientific testable principles that we have today.
And what testable principles are those?
Last I checked, biopoiesis is an unsolved problem, and chemical space is extremely vast -- there are many different ways to organize CHONS life, and there are also ways to organize other forms of life entirely.
Surely "they have to be just like us" is one of the most annoying scientific fallacies.