Is there evidence for Jesus having actually existed? From a non Biblical perspective?

If by evidence you mean written records, then the simple answer is 'yes', bearing in mind the usual limitations that come when discussing literature that's almost 2000 years old and doesn't survive in its original form.

The Jewish historian (and Roman citizen) Josephus wrote a history of Judaism around AD93. He mentions Jesus twice, and these passages have become arguably the most discussed and debated in all of his works, as it is the first mention of Jesus outside of Christian sources.

Why would Josephus even mention Jesus? Early Christianity could almost be described as a sect within Judaism. From Josephus's point of view, it would make sense to include Jesus's life in his narrative, as he was writing a history of the Jewish people up until that point.

It is worth mentioning that out of the two mentions, historians consider one to be controversial, as it is thought Christian authors corrupted the text at a later date.

Ancient authors tended to be influenced by the happenings of their time when writing about history. I believe that the reason Josephus doesn't spend too much time analysing Jesus's life and his early followers is because, at the time of writing, Christianity was still a movement on the fringes of society in the Western part of the Empire, where Josephus was based. He probably did not have much exposure to practicing Christians, and he certainly couldn't have known just how massive the religion would become. From his point of view, it was probably something akin to an interesting footnote or passing anecdote.

The next mentions come a few decades after Josephus, with the Roman writers Pliny and Tacitus. Tacitus supports the narrative of the gospels and says Jesus was executed while Pontius Pilate was the prefect and Tiberius was emperor.

Pliny, if I recall, describes Christians as worshiping Christ as God, demonstrating that since Josephus's time, the Roman literati had learnt more about the tenants of Christianity. Tacitus infamously describes Christianity as a 'destructive superstition' in his work, potentially demonstrating a growing sense of discomfort in Rome towards Christians.

I'm not well-versed on Rabbinic literature and what was said there about Jesus, but as far as I'm aware, non-Christian authors at the time did not question the story of Jesus. Obviously they didn't subscribe to the religious beliefs, but I think it is important to note that they seem content with the general narrative that a prolific Jewish teacher was active in early first-century Palestine, gathered followers and ended up being executed under Roman orders. That's not to say they weren't critical - the satirist Lucian is ruthless in his condemnation, but no one went as far as to outright deny that he was a real person.