Outside of the bible and a couple of writers jesus is practically unknown.
The Bible is a collection of multiple works from multiple authors. Different people, writing different accounts of the same thing/theme. You're compartmentalizing it by modern standards (i.e., the book you hold in your hand as one single work). This doesn't seem like it should deserve being pointed out.
Even so you would think he would gain more notoriety. It's not like people wrote extensive about him either. I mean the bible skips like 15 years of his life. What did he do for those 15 years?
Here's the reality of the times, as far as I understand it. Constantine may have had a dream or vision that led to his adoption of Christianity, but all reliable records indicate it was very much a political move before it was anything else, because not just in Jerusalem and in Israel, but all across the empire, people were converting and spreading the news of Christ the savior of the world. The message and the movement was growing unfathomably fast and large all while remaining illegal and punishable by death.
His notoriety shook up the entire known world in a period of time where nothing was happening, and it "culminated", in some regards, with Constantine, but started well before then.
The lack of documentation of so many years of his life serves as evidence of the reliability of the gospels, if you ask me. If they were a fabrication, if they were a calculated political and revolutionary ploy, they would have taken much more care to address what would obviously have been some serious pitfalls. It's no secret that the story of Jesus Christ takes some reaching to believe at face value. Carpenter from hick-town, born to a whore teenager and an ashamed father, no record of his childhood, is actually God incarnate come to save the world as a begging, homeless servant, and rose from the dead? Surreeeee.