There has been life on this planet for almost 4 billion years. Earth developed rudimentary space travel only about half a century ago and our tech is developing at lightning speed, in cosmic terms. The idea that an alien world would be only a century or two ahead of us is highly unlikely, even if evolution began on both our worlds at the same time.. If they were a century or two behind us they wouldn't be here at all. Even allowing for different rates of technological progress on different worlds it is inconceivable that an alien species would be close enough to our level of tech that we could recognize their machines as machines. They are either WAY ahead of us or WAY behind us. If the latter, they wouldn't have space travel.

Of course, it is conceivable that their technology plateaued and ceased progressing and remained stable at one level for millions (billions?)of years, (perhaps on purpose?), but if that were the case, they would either have not developed space travel at all, or they would be much further ahead of us and their ships would compare to ours like a ours would compare to a dugout canoe.

This is why I am so skeptical of UFO reports. The alien tech always looks a lot like we expect ours to look in, at most, a century or two. Not likely.

The aliens in Star Wars and Star Trek are humanoid and fly ships roughly comparable to ours. They wear similar clothing and carry comparable sidearms. They have alphabets that seem to have evolved from Phoenician and they learn to speak each other's languages and go for drinks at the same cantina. The crews of the Roswell saucers and the Area 51 crash victims look just like the alien scientists that routinely hijack, examine and release redneck motorists in rural North America.

I believe the alien civilizations in "The Expanse" are much more realistic. We won't be able to tell their biology from their technology, and their psychology and culture (not to mention their motives and history) will be totally impenetrable.

The trouble with UFOs is that they're just not STRANGE enough.