[..] There is no doubt that they are out there,
Yes, there is.
We have nowhere near enough information to be certain. We don't even have enough information to make anything more than faint speculation. We know just two relevant things - the universe is very big and that the chance of intelligent life existing is not zero. That's it. That's all we've got. We've no idea how rare it is. We've no idea how rare it is for intelligent life to survive and to develop knowledge and technology even to our current level. It seems to be a whole string of rare things on top of rare things, but maybe there are other paths to it. Maybe the process is inevitable given enough time and suitable conditions. Maybe some higher power is interfering, seeding life all over the place. Also, we've no idea what might happen to a species of people over long periods of time. Maybe some species of people somewhere reached our current level 100,000,000 years ago (not all that long on a universal scale) and are now extinct. Or moved to another universe. Or who knows what. We don't know enough for even moderately solid speculation, let alone absolute certainty.
but the distances are so great that we are unlikely to ever meet them because of the distances involved. We may exchange messages one day, but they will take so long to receive either end that civilisations of any intelligent species will have come and gone in between messages.
Consider this, it would take around 200,000 years to travel across our own galaxy at the speed of light.
Even with some hypothetical form of effectively superluminal travel from anywhere to anywhere, the odds would still be enormous. At a rate of 1,000,000,000 star systems surveyed per year, every year, it would take in the region of 1,000,000,000,000,000 years to survey the observable universe. The chance of any civilisation, even one capable of surveying 1,000,000,000 star systems per year happening to have surveyed anywhere near here within the last 100 years is infinitesimal. Maybe vast numbers of self-replicating robot probes descended from some launched a vast amount of time ago might do it. Maybe.
Also consider that the universe is constantly expanding, at one point we will become part of a cosmic void because everything has expanded and spaced apart so much in the distant future. At one point the void will be so vast that from Earth (assuming it still exists) the night sky will have no stars and no sign of any activity due to the time it takes any light beyond the void to reach Earth's point in the void, and the universe is still expanding... There are already voids detected within the CMB that are so huge that no light will ever reach the centre of them.
Earth will become uninhabitable or be completely destroyed long before that will happen. The sun won't last anywhere near that long on its main cycle. Unless future humans devise and implement a way to keep the sun on its main cycle or replace it with a fresh one or some other barely imaginable solution to that problem.
