Quote from Verenti >>

5th Edition is fairly forgiving and I feel that it can be hard to make a bad character. More important is making a character that appeals to your brother, rather than worry about making an optimal character. An attack score isn't going to keep players coming back to the table, however, an interesting character will.  Beyond that, 5E is set up to tutorialise players with their skills, so just playing a rogue from 1st level should teach him how to play a rogue. Ideally, anyhow.

 My thoughts exactly, only far more eloquently stated.