I think we have to assume there is no one else out there. Too many people see movies and absorb that stuff when much of it is ridiculous. Like having a conversation in real time with someone in another star system. That is impossible according to the laws of physics. To send a message to the nearest star would take about 3 years to get there then another 3 if anyone were there to reply.
Seti has been scanning the heavens for decades and so far have detected nothing but natural stellar sources. In other words, there are no signals, radio, TV waves, or anything that would indicate artificial sources.
There are supposed to be more stars in the universe than grains of sand on all the beaches in the world. If most stars have 10 planets then the number of possible earth-like planets is staggering. Those are the numbers that give hope to those who calculate the likelihood on life elsewhere in the universe. So far we have life only on this planet and no evidence of it occurring or have occurred elsewhere, even locally in our solar system.
There is no hard evidence that other civilizations have visited earth. If spacemen visit other planets they will be from here.
My guess is that intelligent life is an extremely rare and unusual phenomenon and it could be that we are alone. The odds are that we are not but then the likelihood of co-existing or finding other civilizations is remote in the extreme. The universe is huge beyond what we can imagine. We see the numbers but what do they mean to us? We can see a photo of a galaxy like Andromeda but we don't discern the billions of stars that compose it. We are near the beginning of the space age so the future will reveal plenty of surprises.