Sorry, but you are missing the point. Intelligence is an incredibly human-centric concept. Everything we consider “intelligent” behavior, or “intelligent” traits is relative to humans. A good example is how we consider Chimpanzees a “remarkably intelligent species” because they use tools like we humans do. However an ant colony is not considered intelligent even though it has large scale agriculture, social hierarchy and communication techniques we don’t fully understand. And let alone fungal networks which behavior is so alien to us that it could be exhibiting behavior very intelligent to them, but our understanding of fungal life is so limited that we can’t even begin to see it as ‘intelligent’.

If we do come across extra-terrestrial life (more likely through our telescopes, rather then by paying a visit) it will be even more alien to us then our mushroom cousins. It will have evolved in a planet vastly different from us, it might communicate in a way we can’t even think of. Our technology will have more in common with the ant colonies then with the alien technology.

If we do come across extra-terrestrial life and are able to marvel at their intelligence, then I think it will have more to do with our ability to understand things out of our scope, rather then some absolute and arbitrary metric of intelligence.