Old World of Darkness/WMG

The Wyrm is Spiral Power
It's a natural part of the universe, but is feared and restrained because of its destructive potential. Its power often manifests as green flame. Its followers are even known as Black SPIRAL Dancers. Of course, this means the the Weaver is actually the Anti-Spiral(s).

Old World of Darkness is what Creation becomes with the death of The Unconquered Sun
It's a world devoid of Virtue, since the embodiment of Virtue is also gone. His Fulcrums have been found one at a time for brief periods, but no one has had all four (and few have held more than one). The Spear is the most common - you know it as Gugnir and the Spear of Destiny.

The Michaelson-Morley experiment was an actual experiment
In the mid-1800s, centuries of studying the Scourge (Paradox) came together and suggested the Consensual Reality Hypothesis to members of the Order of Reason. The Michaelson-Morley experiment was not an attempt to punish the Electrodyne Engineers by taking away their favorite hypothesis; it was an attempt to test the Consensual Reality Hypothesis by seeing if they could get rid of the ether by changing people's beliefs. (The real-world Michaelson-Morley experiment did not actually disprove the luminiferous ether; it just implied that if it existed, it was behaving very strangely. It wasn't until relativity came along that physicists gave up on the ether.)

All attempts before the Michaelson-Morley experiment to conceal the supernatural can be attributed to the Camarilla or other groups. The Order of Reason opposed the Camarilla and the Masquerade; they tried to empower humanity by telling them how to fight creepy supernatural things like mages and vampires, not by hiding them.

Once the Consensual Reality Hypothesis was confirmed, the Order of Reason realized that if the Camarilla succeeded in convincing humanity that vampires do not exist, then they wouldn't. So they reorganized themselves into something that could better help enforce the Masquerade: the Technocratic Union.

The Sons of Ether defected at about this time. The Technocracy claims that they left because consensual reality can give you your own personal super science that you don't need to share with everyone else, and they thought that sounded like fun. The Sons of Ether claim that they left because they saw the direction the new Union was taking (including lying to the world about the supernatural) and didn't like it.

How do muggles still exist in world full of vampires, werewolves, demons, you name it? They don't.
With so many kinds of supernatural creatures living in old World of Darkness (and it is very possible that there are many we were never told of), normal humans have long gone extinct (if they ever existed in first place). Since every group of supernaturals keeps (more or less) its own masquerade, they keep passing for humans to each other. Your average non-Malkavian vampire is familiar with his kind (althrough even he might have trouble properly recognising more exotic klans and bloodlines and will be very confused at best to meet Kuei-Jin), knows enough of werewolves and Hunters to fear them, might have some knowledge about mages and remember that their blood is hallucinogenic, but he most likely knows nothing about demons, has no interest whatsoever in mummies and definitely does not believe in fairies… so as long as demon, mummy or changeling looks and behaves like humans are expected to, our vampire will think that he deals with mmuggle and act accordingly. He can drink blood out of unfortunate changeling or medium, but he still has no way to feel anything unusual since he never had tasted real muggle to begin with. There was only one truly normal human in history of that world, and that was Hitler.

Oh, and Malkavians? For them it's all clear and obvious. Mixture of craziness, common sense and transformation into vampires causes them to drop Arbitrary Scepticism and expect all Myths To Be True by default, making them unbiased enough to get things right.