Honestly….. I find the whole notion that aliens must be “better" and more peaceful than us extremely naive. I am not saying that they must be aggressive and dangerous, but , it is probably a 50/50 coin toss….
The entire premise that if they are so technologically advanced so they must be spiritually ahead of us is nothing more than us projecting what we would want to be like sometime in the future. But , let’s think it over…
Considering what we know if life ( any life) we can safely assume that whichever possible alien race we talk about, most likely needs food to keep functioning. And food is usually another living being which is lower on the food chain…. So, a race which has been developing for millions of years probably ate quite a lot of other life forms. Now, what has that got to do with Aliens being dangerous to us? Well…. It simply means that all life forms tend to care more about their own survival, and the survival of their race than about any “right or wrong" idea that humans might have. And that life tends to exist on the expense of other life. Now, if, ( for example) a technologically superior race comes from a planet which, for some reason, is doomed- and they need another place ( or it’s resources) to survive then they won’t think twice before wiping away the lesser developed forms of life in order to save themsleves. And this is just one of the options….
When we speak of highly developed civilizations that travel the stars, we don’t know the kind of intelligence we’re talking about. It might be they are all super spiritually advanced, understanding and kind. But they also might function more like a hive- in which case they will have none of the moral/ethical issues we speak off ( and which, as far as we know are purely human, a lion doesn’t think about the suffering of the zebra it kills to feed itself and its young) — maybe, their natural lifespans didn’t allow for efficient space travel- so, they evolved into a mix of life and technolgy (like The Borg from Star track) … a race like that might even see something like colonizing a planet and violently making everyone else like them ( borg again) as doing a good deed , helping the ones they assimilate- even though the assimilated might not see it like that. Again, the same thing that happened when white Europeans decided to help the others by civilizing them and teaching them the “right" religion…. The said aliens might decide that we also need such interventions in order to come to “their level “. …
There are endless scenarios of what might happen, and how will such a race act towards humans. ( they might be a super-advanced race of cockroaches which will feel closer to the bugs than to us and it will want to take revenge for the way we treated their cousins) …. They might be extremely benevolent, wise, kind…an answer to all our prayers. Or they might end up being a nightmare….
If, at least a portion of these reports is true, then they are checking out our military bases, equipment…. Our ways of life and thinking… they are gathering as much info as possible- just like we would have done. Now, to what purpose, that is left unknown.
And until we know being on the cautious side can not hurt….