Have never encountered any technology that does not have a long history of development from terrestrial origins.
Most of the UFO sightings are natural phenomena or military vehicles of of one sort or another.
A lot of the pics I have seen are best explained as LTA ISR platforms, most likely of Chinese origin. .
The infamous tic tacs can be explained by either laser projections or as part of a reactionless drive program the navy has been working on for quite some time. The fact that these sightings occur in military operations areas tend to support that hypothesis.
There are some very legit encounters that are not easy to explain away.
The most intriguing are claims that some of the aliens are inter dimensional beings who possess a knowledge to control unlimited quantities of of essentially free zero point energy and whose existence would have serious impacts on theological underpinnings of human society, especially Judaeo Christian concepts and morality. Not sure what to make of that, but the world sure is primed for their reveal
Interesting...