To prove something does exist, you bring it into the spotlight by using different forms of what might call evidence to narrow down all the possibilities until the one that remains becomes undeniable. To prove something doesn’t exist, because there’s nothing to bring into any spotlight because the whole point is to show nothing is there, you must argue why something can only be impossible by showing how its existence would conflict with the circumstances of things that do exist. For example, we know Superman cannot exist outside comic books because we now know gravity exists as a byproduct of matter itself and that everything that can be touched is matter, which means nothing like Superman can just randomly fly around in limitless ranges of motion, even with the help of “lift” which is the property that allows aircraft to fly, and even that requires a pair of metal invertebrate wings to manipulate the air around it. The things you describe could technically exist with a workaround (hence we have the genre known as science fiction, whose modus operandi is to argue in favor of unsung possibilities, and I myself am not a disbeliever) but not “as we know them” if ghosts for example cannot follow the same laws of matter. If something is metaphysical and above physical limits, it wouldn’t have some physical properties unless they were already metaphysical properties.