Obviously a board game will be easier for a child to compete at than a physical sport. Tons of Rubik's cube world records are held by 9 year olds. I don't see why any of this is relevant in answering the question "is it impressive to be winning at 35 in chess?"

Is your point that young kids have an advantage in chess, making it harder to keep up as an adult? They clearly don't. No 12 year old has ever been able to seriously compete with top players, at best they can hold a few draws or win a blitz game here and there. As far as I'm aware Judit Polgar was the only 12 year old to even break into the top 100, and she's an outlier among outliers. Right now the top 3 players in the world are all in their 30s, and there's only one player in the top 50 who's younger than 18.