Some of the critical characteristics of a successful offensive line is familiarity with each other, cohesion, and execution as a unit. That takes time.
You will notice that the majority of Super Bowl teams had an offensive line with 3-4 starters that played together for several years. That is typically necessary for the cohesion and synchronization required for a successful O-line
The Cowboys had two rookies playing their first game, one at a position he hadn't played since high school.
Tyler Smith lined up between those two rookies. You don't think that created a challenge for Smith?
Again, that front seven of the Browns is one of the best in the league and an offensive line consisting of two rookies playing their first game held their own against that defense.
And here is the important part:
This offensive line will get better week by week as the young players continue to lean and improve.