The teaching attributed to and about Christ cannot be separated from the figure of Jesus, whether that figure was historical or mythical. Central to that teaching is the notion of the messiah.Yes, any and all cultural artifacts are based upon concrete entities and events.What is central about Christianity as compared with other religions is that Christianity's central figure is a flesh and blood person not a holy book.True,Jesus of Nazareth is not easy to find primary sources for, but his socio-historical background is well attested to by primary sources.
What Jesus's socio-historical background has in common with all socio-historical backgrounds which follow upon and take from Axial Age ethic is the struggle between living a good life and prolonging one's own natural life. That is why Judeo-Christianity is still relevant.
There are other Christlike figures who are better attested to by primary sources and some of them are still alive. For historical reasons The Bible survived as the main written testimony. The main historical reason for the survival of all translations of the Christian Bible was undoubtedly the enduring political power of the RC Church, its antecedents, and its powerful adherents.