To be fair, Josephus has only two quotes about Jesus, and one is definitely a forgery, although it is debated if it is a full or only partial forgery. The other quote is considered authentic, but just mention "James, the brother of Jesus". So not a lot to go by.
But you are correct that historians generally consider Jesus to be historical. It is not so much due to Josephus though, but more due to critical reading of the Gospels themselves.
The quote you claim as a forgery has been a subject of much debate, but I'm relatively certain it's not been proven to be so and many consider it to be at least partially authentic.
Regardless, Jesus was absolutely a historical character. No serious historian debates this.
The passage outright states that Jesus was the Messiah, which means it is obviously a forgery - Josephus wouldn't have written that since he wasn't a Christian. But the question is how much of the passage that have been altered.
The discussion has generally been that some people think that statement was added. There’s quite a bit more to it though, and that’s certainly not the only possible - or even obvious - conclusion.
And I guess you’ve never heard of Josephus? He’s only the most well known Jewish historian since Moses.
Jesus most certainly lived, no serious scholar of history claims otherwise.