You're argument about the distance involve ruling out aliens is specious. There are probably a half dozen articles about the possibility of warp drive, even by NASA scientist. So, the distance factor is only a question of technological feasibility. Just because we can't doesn't mean it's impossible.

You acknowledge that UFOs exist. That's huge. I like that. As a UFO fan, and a speculative alien fan, I acknowledge the presence of UFOs. Now that we agree on that, there is really on three possibilities. Either's it's artifact of consciousness made manifest, as proposed by Jung in his book on UFOs, or they're advance technology made by us, or they are aliens. I am happy for it to be any one of these three options, because they're all interesting in their own right.

Except, the second one. If it's our tech, and we have things capable defying gravity, or known laws of physics, operating on better power sources than what's publicly available, then the nations that have access to this and aren't using this tech to help us reduce carbon emissions and improve life are criminally liable for extending humanities ignorance for questionable reasons. I'd rather it be subtle, quiet aliens that are so ethical they don't want to unduly disrupt the indigenous populations, just as modern anthropologist would avoid contamination. The latter means there is a universal ethical standard. The other, well, that's just more evidence of human fear and greed.