The quest for the historical Jesus is a very long and complex one, and it would take a book to do it justice, but I hope this helps answer your particular question.

First off, I don’t imagine we’ll ever get any primary sources regarding the life and teachings of Jesus (although that might depend on what you consider a primary source). Even the Gospels were written decades after his death by unknown and disputed authors, and Paul, whose letters are the earliest part of the New Testament that we have, never actually knew Jesus during his life (whatever you believe about his alleged vision of Jesus later on). Everything we have to go on, as far as I’m aware, is secondary regarding the actual life and work of Jesus of Nazareth: accounts by others and retellings after the fact.

Secondly (finally getting started on what you’re actually asking about!), I’m not sure there are any sources specifically regarding Jesus’s public ministry or what he taught outside of a Christian perspective. (There certainly are sources for that that rare non-Biblical in the sense that they didn’t make it into the Bible, but they’re still Christian sources, which I imagine is not what you’re looking for.) For non-Christian sources that can be used as evidence of his existence, the two main authors that scholars usually point to are the Jewish historian Josephus and the Roman historian Tacitus, both of whom mention him in their writings in the first century CE.

Josephus’s “Antiquities of the Jews” describes Jesus as a Jewish preacher who claimed to be the Messiah and was crucified on the orders of Pontius Pilate. There are other mentions of him in the work (that is, in the very same passage in which Josephus discusses him), but they’re generally held to be later Christian interpolations (phrases added into an existing text later on by a different author) because they explicitly state that Jesus in fact was the Messiah. However, I believe most scholars agree that there is some kernel of truth to whatever original description was made of Jesus as a Jewish preacher who attracted many followers before his crucifixion.

Tacitus refers briefly to Jesus in the context of first-century persecution of Christians, noting that they were blamed for the Great Fire of Rome by Nero and that their leader (Jesus) had been executed by Pontius Pilate in the reign of Emperor Tiberius. It’s a rather harsh passage regarding Christians themselves (Tacitus was a Roman senator, after all), which would lead one to believe that it is more authentic than the passage in Josephus’s Antiquities.

As stated previously, those two works are not primary sources about the life of Jesus. What they are is evidence that non-Christians in the Roman Empire were aware of the spread of Christianity in the decades following Jesus’s death, that multiple non-Christian historians believed at that time that Jesus did exist and was crucified, and that afterwards his followers continued to grow into a mass movement.