Living observers are not necessary, just demonstrated reliable sources. In this regard, I may be amiss in my assessment of the Okapi sightings, since I don't personally know the reliability of the observers.<quoted text>
Then you contend the same about the Yeti, Bigfoot, the Loch Ness Monster, UFO's? Because there are living witnesses they are not "imagined", just unverified by science?
Then you contend the same thing about the Holy Grail, Noah's Ark, the Ark of the Covenant, the Ten Commandments? They have been sought for decades, centuries, millennia - and since they predate any living observer by at least 2,000 years, they are as mythical as Quetzalcoatl and Excalibur?
Except for the Biblical references, the entities you mention are not attested by demonstrated reliable sources.