The chemical elements, the laws of physics, mathematics, geometry are universal constants and therefore a common reference. Whether that's enough to enable meaningful communication is a separate question ... but we absolutely do have common references.
We are conditioned to believe that those alien cultures are vastly more intelligent
"We"? Who's "we", Kemosabe? Any regular reader of science-fiction will have encountered stories with aliens ranging from barely smarter than a dog to super-geniuses, and ranging from like us enough to be nearly carbon-copies to so utterly different as to be completely incomprehensible.
What if an extraterrestrial culture is familiar with chemical elements we know nothing about or they don't know about ours?
What if we find our understanding of the speed of light is arbitrary to our method of measuring not theirs? What if their laws of physics are based on their understanding of the limits of their physical world, not ours?
What if their reality is based virtually not physically?
Almost all entertainment media depicts alien cultures as super intelligent and easily capable of talking the english language. Like it or not, that is the layman's perception of a future encounter.
What if they interpret our intelligence by intercepted TV shows like...well anything on TV now.
Make no mistake about it, I believe there are lifeforms in the universe other than ours, it is statistically inevitable. I just believe that any encounter would be entirely coincidental not intentional and they would be as equally unprepared to deal with us as we would be with them except in one instance. Total domination by the superior culture.