I'm not sure Tua is really better than Jones if their positions had been flipped the last two years. The stats of their first two years in the league are very similar (Tua 66.2% completion, 27 TDs, 15 INTs, 194 yards/game, 88.8 rating, 5.5 completed air yards/completion; Jones 66.5%, 36 TDs, 24 INTs, 219 yards/game, 89.0 rating, 5.6 completed air yards/completion) and the quality of their play in college at Alabama was also not that different (and potentially even with edge to Jones if you consider that Tua had the luxury of throwing to 4 first round receivers at the same time with DeVonta Smith, Jerry Jeudy, Henry Ruggs and Jaylen Waddle).
The difference is in my eyes mainly the quality of the receiving corps. It's easier to get the ball out fast (and throw deep) if you have Hill and Waddle lining up next to you than DeVante Parker or Demario Douglas.