Many people try to force such things into a preconceived mold or a popular narrative, whether they fit or not. It's hard for many people to live with uncertainty.
The MSM tends to conceal such reports as resolutely as they conceal unwelcome information about their favorite political candidates.
One of the most interesting was a report from Peru several decades in which a member of the Peruvian Army, on maneuvers, went to investigate lights in the distant mountains and returned a few hours later, confused and with a several days' growth of beard on his face.
To jump to conclusions about such unexplained phenomena is silly--especially to deny outright the veracity of such reports.
Yes, history is full of unexplainable phenomena.
Few consider them as signs from God, but that is as logical
of an explanation as any.
You mentioned crop circles, one of the holy grails for UFO buffs.
I was in Romania for an evening, watching a cable TV program on crop circles.
It was very detailed in how they are made, down to where they even heat broken crop stalks to make it look like it was from radiation.
Crop circles have become a true art form.
If there is an ET on Earth, it is Obumbo.