Perpetually Mistaken

Memory spirits are attracted to historically important events or moments that are about to cause a butterfly effect in history.

The orbs of light (and all the other characters that appeared before Lachlann in the mansion scene) in the Moonshine animatic as well as the ones surrounding Oskar in the Partner in Crime animatic and the ones surrounding Ed's dad in one of the shorts are memory spirits

They are known to reside in empty/abandoned places and often recreate either happy or violent events that happened in them. Because of this, they are often mistaken for ghosts.

There are two types of dragons, ones that are more humanoid (basically dragonborn) and ones that are not. Like a lot of other species in SaS, those who were not able to integrate with humans faced extinction. By the modern times, a lot of them have already disappeared.

The most common types of merfolk come from shallow water. Deep water merfolk (like Lucius and Oskar) still remain a mystery.