"these Christians" were rather obviously following something, some teaching.
But being honest, I can't find that either. I would imagine that if such an actual identifiable individual were proven it would make the news at the very least.
Oh, sure. There clearly were Jews in that region who for many centuries had believed in the coming of a
"Christ", i.e. a messiah.
Though since the time of the Dead Sea Scrolls c.170BC through to 70AD, it seems Jewish messiah preaching had been in a state of change, probably influenced by various god beliefs introduced by the Greeks, Romans and Persians, inc. preaching very similar to the later beliefs of Paul, where instead of a human military leader in the line of King David (who himself appears to have been only fictional anyway!), where both the scrolls and Paul appear to be preaching of the messiah as a divine priestly figure ordained by Yahweh in heaven and who had been sent specifically to gather the faithful ready for Yahweh's day of final judgement which was believed imminent at any moment.
But exactly who any of those different preachers and sects thought that divine apocalyptic messiah was, seems to vary from one preacher or sect to the next. Paul apparently thought he was the messiah named 1000 years before by Moses as
"Yehoshua" i.e. Jesus. The Essenes of the DSS only named the messiah by the coded epithet
"Teacher of Righteousness". Paul is supposed to have referred to earlier Christ believers who he had once persecuted, but in certain of Paul’s letters he appears to admonish the leaders of those earlier existing
"Christ" followers for believing that various different people were
"the Christ".
But the teaching they were all following was rather obviously their belief in the OT. The only problem with that was, the prophecies and statements in the OT were often deliberately vague and left open to all sorts of interpretations as to what anyone thought the passages really meant.
Paul is very clear in his letters in saying that he had used that OT scripture to discover the true meaning of the messiah prophecies. He clearly says that he believed that
"God was pleased to reveal his Son in me" (that from memory), where he is talking about his belief that all his constant attempts to communicate with God and to receive & understand Gods great secret message etc., had been rewarded by God giving him the gift of revealing from the OT the true meaning of the divine message that iirc Paul says was the great
"secret" "hidden for so long" ... and that great secret which God was pleased to reveal in Paul, was the revelation that the OT passages actually meant that the messiah had been a divine messenger of the past named Yehoshua (Jesus), named by Moses himself!
So if the above is roughly correct then it does not seem to me that there needs to be any great mystery about where any of that messiah teaching came from. It very clearly came from their absolute and total faith in the OT as divine revelation from God. And in fact both Paul’s letters and all the gospel writing specifically says that the authors were obtaining their messiah beliefs from that OT scripture. So I don’t see much room for any doubt about that at all.
And nor do I think there is any great mystery about who these earlier
"Christians" were. They were all the Jews of that region, every last one of them. All of whom were absolutely certain that their divine OT promised as matter of certainty that a Christ would appear to save them ... the only caveat, which had lasted since at least 500BC if not 1000BC, was their constant debate about exactly who God’s messiah was or would be (depending on whether they thought he had already appeared, or whether they thought he was still preparing to appear) ... where at various times different preachers like Paul and different sects such as the Essenes, had variously claimed all sorts of different people as Yahweh’s promised and utterly certain coming messiah “the Christ“.
