Only if said newcomer is aware of the new definition. If someone is unaware of the meaning of 'sasquatch' or 'yowie', using a new word isn't going to clear up the confusion. Instead of spending time defining and then disseminating a unique word to encompass all reported BHM's(Big Hairy Monsters) no matter how varied the description, why not just educate people about their local creatures and how those creatures may or may not be related to others around the globe?
Ironic, then, that someone who avoids labeling things advocates lumping all types under one label which you admit will likely be inadequate without further refinement. Admittedly, I'm not sure I fully understand your second sentence in this quote.
Whaaa...? Seems self-contradictory. You want to group different creatures under one name so people will better understand how they're the same yet different? The whole idea seems like a solution looking for a problem.