Now the thing is the first entry in the Journal of Facts is that
the first line in it,written by some gal named
Morgana LeFay way back when
states that
"Dragons do not exist"
However,since the cover of the Journal is made out of
dragon scales,the thread used to sew all the pages together is composed of the fur of a unicorns mane
and the glue binding is made from the spit of a kraken
clearly a Journal made out of the materials from a creature
Morgana LeFay claimed didn't exist is a contradiction.
In actuality the Journal of Facts has a built in Fail Safe
mechanism,thanks to it being made from supposedly non existant creatures
that keeps folk from writing themselves out of existence.
So when Noah had accidentally written himself out of existence the Fail Safe had kicked in.
Though humans could no longer see Noah,dragons,unicorns and krakens still could.
So it was that after Noah recovered from his accidental
non existence he had gotten up off his bed and after fruitlessly
trying to catch the attention of the McCoy family
he had concluded he had somehow phased into another dimension.
Which was more or less correct.
So he gathered up some food,which apparently didn't care if he didn't exist anymore,packed some stuff into a rucksack
and headed out of the eerily ghostly McCoy house and went out
exploring this new reality where though he could see humans
they could not see him.