https://en.wikipedia.org/wiki/Historicity_of_Jesus
Josephus is an often cited but sometimes controversial source.
https://en.wikipedia.org/wiki/Josephus
https://en.wikipedia.org/wiki/Josephus_on_Jesus
The scholarly consensus, not just among "Christian" scholars, is that in some passages he refers to both Jesus and Christians. However, this was written in 93-94 AD, so, about 60 years after the putative death of Jesus. There might conceivably still have been people around who knew him "in the flesh".
Fwiw..."
Virtually all New Testament scholars and Near East historians, applying the standard criteria of historical investigation, find that the historicity of Jesus is effectively certain[3][4][5][6][nb 1][nb 2][nb 3][nb 4]although they differ about the beliefs and teachings of Jesus as well as the accuracy of the details of his life that have been described in the gospels.[nb 5][12][nb 6][14]:168–173 While scholars have criticized Jesus scholarship for religious bias and lack of methodological soundness,[nb 7] with very few exceptions such critics generally do support the historicity of Jesus and reject the Christ myth theory that Jesus never existed.[16][nb 8][18][19][20]".
By contrast, the Epistles of Paul are dated to about AD 50-60 from internal references, largely, if I remember correctly.
Tacitus does mention Christians as well.
"
The Roman historian Tacitus, in his Annals (written ca. AD 115), book 15, chapter 44.[43]describes Nero's scapegoating of the Christians following the Fire of Rome. He says that their founder was named Christus (the Christian title for Jesus), that he was executed under Pontius Pilate, and that the movement of his followers, initially checked, then broke out again in Judea and even in Rome itself.[44] Some scholars question the historical value of the passage on various grounds.[45]"
You might find the article interesting: it's pretty balanced in its presentation.
https://en.wikipedia.org/wiki/Historicity_of_Jesus