You are, I think, reading too much into alt's post. alt did not say we are unique. There is a huge, huge gap between "we are alone" and "we are unique". Suppose intelligent life is rare, rare enough that only a few billions of planets in the observable universe harbor intelligent life. Being one out of a few billion means we far from unique. However, a few billions of intelligent species in the universe corresponds to one per 100 galaxies or so. It would put our nearest intelligent neighbor in the next galaxy cluster. That certainly would qualify as "all alone."
We don't know if life is common or rare, let alone whether intelligent life is common or rare. Extrapolating from a sample size of one is always a bad idea. That said, I side with alt. I don't believe in ET in the sense of visitations by ET to our planet, ancient or current. It is to me the easiest answer to the Fermi paradox.