While it was neither "Messianic Judaism" as practiced today, nor was it a group that considered itself independent of the other Gentile congregations around the world, according to reliable tradition and suggested by records and DNA, some of my ancestors were possibly members of the original Church in Jerusalem.
Though a Catholic Christian, I am of Sephardic Jewish ancestry. I grew up in what is referred to as a Crypto-Jew family, practicing long-held Jewish cultural traditions and speaking a rare Jewish language known as Ladino. While recent laws of return from Spain and Portugal have highlighted even more detail for my family about our lineage, it has been suggested by some researchers that a few members of my family line are traditionally connected to the ancient Jerusalem church.
The limited record for this group is actually part of Roman Catholic history as this church had connections to the movement that eventually divided into the Catholic West and the Orthodox East. According to this history, the last Jewish bishop of Jerusalem was Judah Kyriakos, the great-grandson of St. Jude the Apostle. When the revolt under Bar Kohba was crushed in 135 A.D./C.E., this group, which held St. James the Greater as their first bishop, disappeared.
The Sacred Liturgy of the Mass, according to tradition, originated with James the Greater, and current Catholic and Orthodox services are based on this incredibly lengthy prayer ritual which still exists in several extant versions.
The group was Christian but culturally Hebrew, or Jewish, and as such observed Torah but held faith in Christ. (Acts 21.15-26) Some members from this congregation may have been the Judaizers who caused trouble for Gentile Christians in Galatia. Members from this group, described in Scripture as those "from James," who came to visit Peter while he was there influenced the fellowship division that led to Paul's rebuke of Cephas.--Galatians 2.11-14.
However the group neither saw itself independent of the rest of the Church nor was it composed of Gentiles, being centered in Jerusalem. But exactly what happened to all the members when the revolt of 135 demolished the last Jewish communities of the era is unknown. Some of this group traditionally arrived in Seferad (Spain and Portugal) by way of Rome and lived among the Jewish community there until 1492 when the Alambra Decree expelled all Jews from Spain.
Some of the records of a few of my ancestors who suffered during the persecution of the Spanish Inquisition (the Catholic Church actually kept detailed records of the horrible things they did) have inquisitors teasing and mocking the claims of some of these victims, namely that they were of the House of David. While some of these were forced converts, some apparently were not.
After being expelled from Spain in 1492, over several generations my ancestors traveled into North Africa, crossed the Atlantic, traveled into Puerto Rico and Cuba, and eventually settled in Mexico where they founded the city now known as Monterrey. The short-lived Mexican Inquistion chased many further into South Texas, but the horrible death of one of my ancestors in Mexico who leaped to his death from a window after being cornered by inquisitors seems to have played a part in bringing the end of the Inquistion era.
It took about 20 years, but with the help of various historians, linguists, the governments of Spain and Portugal, the Catholic Church, and a number of rabbis, my family was able to assemble a history that we can trace back to Jerusalem. The stories about the Jewish Christians under St. James are choppy, limited, and incomplete however. Some of what is known is merely long-cherished tradition, hampered by centuries of persecution and struggle, but still present nevertheless.