I mean, yeah...
The Bible wasn't some dude writing stuff down. It's a bunch of dudes over centuries writing stuff down, and doesn't include everything.
It was commone with the pre-christian religions for myths to work like that, and as Christianity co-opted different parts of those earlier religions to make conversion easier, people.kept making up stories about Jesus or saints like people used to make up stories about Zeus or Hercules.
If Jesus's 20s weren't conspicuously absent, it prob would have been pretty close to Chuck Norris. Just because those stories didn't stick around, doesn't mean they never existed.