The Bible is divided up into a series of multiple, smaller, books (you may have noticed that). Each one having a different origin and purpose. For example, a lot of the New Testament consists of Paul's letters to the various churches that were being established. Psalms is, quite literally, just a song/poem book written by David. Song of Solomon is basically a compellation of love letters/poems shared between Solomon and a lover (I forget who). Saying that they're religious or historical is like saying all video games are RPGs'/Shooters. While there may be some that fit the criteria (like Genesis being religious) others simply are not that. They may all have a religious PURPOSE but that's not the same as being a religious BOOK.
We have four books that exist which detail first-hand accounts with the person. Multiple people who were directly antagonistic to Jesus though not once doubting that he exists (remember: Saul was antagonistic to the new religion and did his best to undermine it before being converted). The Catholic Church was founded by Peter who was Jesus's BFF.
I can understand doubting that Jesus was the son of God. But doubting that he EXISTS? We know more about him than we do some kings. And I don't see how it's not hypocritical to say that some other figure from ancient history, like Leonidus, existed but then IMMEDIATELY nope out when someone implies Jesus did. That seems utterly hypocritical and non-sensical to me.
I mean, you're assuming that people like Paul and Peter are real people though. I would dispute that and say that potentially none of these first hand accounts are actually by these so called individuals