As to "why shiny craft in the sky", we get patterns of light in the -vast- majority of situations. We have an optical system trained by millions of years to recognize patterns; throw in any sort of stimuli that doesn't fit the expected patterns, and our minds will still try and categorize it.
What you'll note we're not seeing are detailed craft with any sort of definition to them. As you say, no flying spaghetti monsters, but also not even something more complicated than an orb or a disk. Not even an orb with a decal on it. Not even as described, let alone the photo/videos. Just light and reflections. Even the Chinese surveillance balloon had more texture to it in its images and descriptions, and you'd at least think we'd have seen a spacecraft with some branding or customization, the equivalent of a Spitfire's Roundels or a shark's mouth decal or an identifier a la NCC-1701.