Bearing in mind there are not only countless trllions of stars around which circle trillions of planets, we still have billions of dimensions which the human senses cannot detect. Our sense of sight covers an extremely narrow spectrum, yet some of us have this crazy notion that "if we can't see it, feel it or hear it " it can't be real - this despite radio!
Why would something as infinite as Nature, or the All Mighty -whatever you believe - focus on and only create (or evolve) living species on the third planet out from a very average-to-middling star (our sun) in just one of the myriad gallaxies we can see? What's make us so special?
It has been hypothetized that the reason other beings from other worlds don't make contact with us in a meaningful way is because humans can't be trusted. We haven't grown up yet.
Oh, and If you think we have, then I suggest you just turn on the evening news tonight to get an idea of how we're still treating one another. How, then would we treat what we regarded as an alien species?