Good evening,
Like you I am a beginner as well and from from what I see on YouTube on videos that show the construction of Ukes these are just glued on. You can certainly try cleaning out the joint with a piece of fine sandpaper slid under the neck and gentle rubbed back and forth to clean out old glue and then with a toothpick or even a needle try forcing some wood glue back into the joint and then with a bit of rope or even a belt force the neck back against the body for the glue to set.
Chip