RB is a different animal than playing QB, it is a lot easier to be successful at RB than probably any other spot on the team.
With that said I think DR will be successful this year.
Yes. 100% yes. There are certain positions where it is not uncommon for Frosh to compete as starters. They are generally RB, WR, CB, and Kicking specialists. Mainly because those positions are as much about physical talents as opposed to size and strength. If you are fast and have decent vision you can be successful at those positions as a frosh.
Less Likely are LB and QBs because in addition to physical abilities they require a higher level of football knowledge. They are the leaders of their perspective sides. So comparing them to RB, WR and CB is just not a good comparison. If you have freshmen starting the first game of a season at those positions. It usually means you were not good there the year before.
OL and DL are the rarest of all to see start as Freshmen. Mainly because there is a strength and size difference.
All that being said. We were not very good last year at QB so this is the perfect set up for a generational talent to start as a Frosh. Additionally, it is rare for QBs to regularly get coaching from current NFL QBs starting in Middle School. In college football right now there are 2 that had that advantage. Arch Manning, and Dylan Raiola. One is from the most successful QB family in NFL history. The other's father was a center and got the guy who he protected to teach his son a thing or two. Taht same person is being coached by the same coach that is coaching the best QB in the NFL right now. As a result he also works out with that same QB when he has a chance. "Next weekend I will be going down to KC to work out with Mahomes." Dylan Raiola. after the spring game.
Add to all that that with his dad's genes he is larger and stronger than most QBs. Making him more durable to hits than the average Frosh QB.
Does ANY of that mean he will be successful as a frosh? Sadly, no. What it does do is increase his chances of Success.