Do aliens exist? Logic suggests a very strong possibility that they do.
Have they ever visited this planet? The same logic suggests that is unlikely, at least under the laws of physics as determined by our current understanding. So, I rather doubt it.
I would suggest that a very large proportion of so-called alien/UFO aightings are either totally fictitious or the result of flawed observation or comprehension of what was being observed. But, is there a core of genuine sightings hidden in that morrass? Dunno. I haven't made up my mind either way, because I have no hard, credible evidence either way.
As for the paranormal, I'm dubious but open-minded. I have experienced a few things I struggle to explain, but I suspect that is a lack of understanding on my part, not anything paranormal. But I certainly don't discount the possiblity that paranormal activity actually occurs, because I have no way to prove it doesn't .... or that it does.
In other words, on both counts, I have doubts but no concrete opinion.