I'm no expert, but think the Coptic sects accepted early Roman orthodoxy, participated in the various councils, adopted the Nicene creed, condemned the various heresies, etc. So they differ extensively from the rather heterogenous beliefs and practices of the church of 1st and 2nd century.

In a way, maybe Islam is closer to what you're suggesting. A monotheistic religion without the dominance of the Roman empire or influence from it, and without the rather odd violent debates about the trinity and the relationship of Christ to God etc. that went on in early Church