Yes, there could be alien life out there. The universe is very vast and greatly undiscovered. With all that there is to be discovered yet it would be slightly foolish believe that us humans here on Earth are the only single living life forms. It makes much greater sense for there to be, or at least to have been, other life forms in other places of the universe.
Yes, there not only could be but certainly is alien life out there somewhere. How narrow-minded is it to assume our planet is the only one in the entire universe with life on it? We probably haven't found an inhabited planet yet, but even if we did find one, would we recognize it? Our narrow human thinking may not allow for life in other forms. We'd probably miss it if we saw it.
Alien life could form on a planet that is similar to Earth and has all of the things necessary to sustain some sort of life. This could be simple microbes or creatures like dinosaurs, depending upon the planet's stage of development. Equally, the plant might hold intelligent life forms that visit us regularly to monitor our progress. This could account for all the UFO sightings.
Too many assumptions maybe based on too little facts. I know the redshift method can detect planets in stars, but based on these observations isn't it risky to say that they detected just one planet orbiting Proxima Centauri? Can't those signals cover more than just one planet? Too many questions arise but the technology is not just yet there to answer them, but that also maybe shows that these assumptions are just that, assumptions not facts.