Only those exposed to the doctrine of the trinity would come up with a belief in a triune god.
However the real issue raised by discussing John 1:1 is the fundamental ambiguity of the nature of the the NT God.
The Hebrew myth shows an evolving god as the culture absorbed the ideas of its neighbours over time. Moving from a god who was someone you could talk to and argue with, to the rabid despotic deity who heartlessly would to kill all who didn't worship him. Simple reflections of a primitive society trying to raise the status of their fighting prowess. The OT god was the creator of good things and the bringer of evil as well. But although a son of El and having sixty nine brothers, Yahweh was always singular in nature.
So we might usefully ask why the NT god is so different? Surely God doesn't change?