It is a good point. We like our forgeries to be as old as they are supposed to be. Then again, sometimes they do report factual details, or accurately tell us what somebody at the time wanted believed.

Best scholarship today says there was no person who walked around Judea telling the parables related in the gospels. It all seems to have been made up two generations after the cult started.

Congregations demanded a person to have told the parables, and a narrative about where and when they were told. "Mark" is that narrative, with the other three gospels cribbed from it adding doctrinal "corrections" favored in different places. ("Mark" etc. names were pasted on centuries later; nobody knows who wrote them.)

The only otherwise-plausible bits of evidence of such a person, in Josephus, are transparent later insertions. Pliny and Tacitus, often cited, only repeat what they had been told Christians believed.

Third-century Church authorities were thorough in destroying all documents they controlled but what they chose to put in the Bible. In later centuries they fabricated industriously. So almost everything claimed to be contemporaneous is transparent fakery, Paul excepted. Pauline material is cut'n'pasted freely, and often doctored, sometimes even accidentally.

See Richard Carrier, "Why Invent the Jesus?".