Hello, I believe UFO sightings fall into several categories. There are outright hoaxes. Sightings of explainable phenomena or man made objects and finally a small number of totally unexplainable objects.
Hoaxes are just that so no real need for explanation.
People may see explainable phenomena, ice clouds reflecting sunlight, an experimental aircraft etc. These are genuine cases of mistaken identification. People see an object in the sky and cannot initially rationally explain it, I have witnessed what many people thought was a UFO over my home town in England. It was a long key shaped object which appeared in a clear sky one afternoon. Considering the matter it was possibly a meteological balloon, the long thin body the stem of the key with the rounded top the ring on a key. Catching the sun at an unusual angle made it shine, then as the angle change the reflected light moved in a different direction, many claimed its sudden disappearance was a rapid acceleration in its speed.
The final groups are items which defy normal explanation, you can include in this ball lightning which still needs some study.
Do I think many sightings are of extra-terrestrial origin, no. I don't doubt there is extra-terrestrial life elsewhere in the universe, but I think most UFO sightings are of phenomena found naturally here on earthh or man-made objects rather than beings from other planets.