It just so happened that Paul's gospel version won out, as his appeal and acceptance among gentiles was greater, and Jerusalem (The temple, etc. fell) and the original Jewish followers of Jesus dispersed. Within the first few centuries, there was a diversity of branches influenced by Jesus or a 'Crestus' figure, who were also called 'Chrestians' by the earliest term, a word which was later changed to 'Christian' in the centuries following, but thats another thread. So, sure you have the community of Jesus followers in Jerusalem still holding to the the essential tenets/traditions of Judaism, with some innovations brought in by Jesus own teaching, and then Paul's gospel that was quite different, so that some with more Jewish proclivities held to the Jerusalem centered religious teaching (upheld by Jesus original apostles, the pillars Peter, James, John, etc.) and then Pauls gospel was another tangent, if not its own unique dispensation.
Do note the distinguishing content of the teachings and that Paul himself boasts about having his own gospel, and even dissing the original apostles, elevating himself as God's messenger more or less (see Galations, etc.). There are messianic believers in Jesus as Messiah who reject Paul, and hold to some messianc form of biblical practice, or somehow reconcile Paul's teaching. That the greater Gentile world accepted Paul's gospel and the NT interpreted as a synergistic whole, is a matter of biblical 'convention'. Of course the greater percentage of modern day Christianity champions Paul's gospel of grace, interpreting all thru the lens of it, but I think there's more to it, and this is more often brought up by secular and religious studies scholars, that do not play to traditional concensus but strive for a more objective approach without having any religious presuppositions or bias. Anyways,...just saying there is more involved outside of conventional belief systems, mythological motifs and hand me down theologies.
Since the death of Jesus, and his resurrection is a central theme in the NT, naturally the doctrine and theology will be based/contextualized upon the 'event', 'theme' or 'allegorical context' of the 'story', all the gospel narratives serving that story line, where then Pauls letters and other epistles offer deeper explanations of various aspects of 'doctine', Paul's letters being earlier than the gospels, and then some later epistles reflecting the ecclesiastical leanings and church politics beginning their formations.