Yes, Kirk is incredibly young for a starship captain, Picard by comparison could have been the older brother of his father when he took command of Enterprise.
Although he took command of the
Stargazer when quite young, at the age of 28. At least, that's how it's been retroactively interpreted. I think the original idea was that he served aboard the
Stargazer for 22 years and eventually became its captain, but the
Chronology and the novels have assumed that he became its captain almost immediately. Per "Tapestry," he took over command when the captain and first officer were killed and then got to keep command thereafter (i.e. almost exactly how Kelvin Timeline Kirk got the
Enterprise in the later movie).
Roddenberry cribbed a lot of TNG's basic ideas from
Phase II -- Riker was Decker, Troi was Ilia, Data was Xon, and Picard was meant to be the older, more experienced Kirk who took on Decker as his protege (with Decker taking over as the young action/romantic lead). So Picard was conceived as a character who had already become renowned for his past successes and was now a mentor to the next generation (to coin a phrase). The original writers' bible stressed that Picard was considered a legend for his unparallelled record of discoveries and first contacts aboard the
Stargazer. That's why he was deemed worthy to command "the flagship of the Federation" -- because he was already the best of the best.
But TNG so rarely talked about Picard's pre-
Enterprise career that a lot of fans forget it existed. Like, one of the criticisms you often hear of
Nemesis is "Why would the Romulans have cloned Picard if he wasn't famous yet?" But Shinzon was only about 25; according to the novelization, he was born in 2354. At that point, Picard would've been the
Stargazer's captain for 21 years, more than enough time to establish himself as an important figure in Starfleet. But even Memory Alpha dismisses the importance of his
Stargazer career in discussing Shinzon's origins. People just assume that if we didn't see it, it didn't matter. They never think about the fact that his
Stargazer career was an even larger part of his life than his
Enterprise career. And really, given that fact, TNG itself should've addressed it more often.