There are some ‘fringe’ elements of science that have become too common to be nothing. I’m not sure UAP are alien space craft but what if they are a some other form of life, flirting across our atmosphere. These things often follow aircraft not like a fighter escort but a dolphin following a ship.

We know that reality operates on multiple quantum levels we cannot see or physically interact with; what if there is life at other levels skipping through our neighbourhood, more animalistic than sentient?

‘Ghosts’ are another. We know precious little about the depths of the human brain and how we interact with the quantum universe on a background level. Humans give off EMF and we know that EM signals can be recorded. What if some traumatic event for a person leaves a kind of ‘quantum recording’ in the fabric of space-time that sometimes plays itself back?
Makes more sense than spirits of the dead!

‘Poltergeists’ have long been theorised to be latent psychic interactions with physical objects, often from individuals experiencing puberty.

It may be that what we widely assume are paranormal events are just in fact scientific phenomena we do not understand yet. Remember at one point we thought the Sun and Moon were both deities of some description!