IMHO, extraordinary claims require extraordinary evidence.
I think we have all looked up at the sky and simply 'blown off' objects we have seen there as something mundane, even though we did not know what that was.
The more experienced you are at observing, and the more you know about flight dynamics, velocities, etc., the more you can comfortably classify as ordinary human activity, but when people with that experience note anomalies that transcend the boundaries of their knowledge and experience, then it is noteworthy.
We do not have all the answers, and I lack the evidence to rule out any possibility, and after that probabilities and explanations become a refuge for those who do not want their understanding of the universe to be challenged.
Might there be "space aliens"?
Sure, if there is intelligent life out there, they likely will be exploring, too.
They may have been doing so for longer than we have been writing down our accumulated knowledge and beliefs, and be far more advanced, technologically, than we are, or perhaps only have taken a different track with their core beliefs and axioms that permitted that growth to occur, which might even be based on different sensory perception which enables them to see and study phenomenon we rely on instruments to sense, leading to different propulsion technologies and trans warp speeds (and the stasis fields you'd need to accelerate to those velocities).
...or simply discovered the secret to quantum coupling and teleportation.
I am open to proof, but remain unconvinced.
Now we see through a glass darkly, and then, face to face.
