Definitely not. Kids that age want to run and climb and have fun. There’s just nothing for them to do on the Navigator.
I was on a cruise in the Med on the Voyager. There were three boy cousins with their Moms and Grandma. Kids were around 8 years old. Well, near the last day, the Moms had a loud argument by the pool, with 2 of the sisters yelling they wanted to take the boys on a Disney Cruise and how horrible the Regent cruise was for school aged kids.