The term "God" is very modern. If I recall correctly the first translation of the Bible to use that term is the King James version - about 1610.
Prior to that Deus was used - from Latin - that seems to come from Sanskrit, meaning "shining" and "celestial".
And of course there are various ancient accounts of the gods in their shining craft.
The standard human format, when properly controlled, refined, aligned and intentional, has direct awareness of The Source of All. Thus the standard human format is connected both to Existence and to pre-Existence.
The mystics, perceiving their own unity with The Source of All, needed a concept that reached before the heavens existed - but that was not too offensive to the Holy Inquisition.