For smaller RV's all you need is a regular drivers license and after you have your regular drivers license you can legally drive the RV.
Basically as long as the RV doesn't have air brakes then you can drive the RV with a regular drivers license.
If you're new to driving and are only driving at 16 years old then you could legally drive the RV if you have a regular drivers license.
But driving an RV requires some more experience than just driving a car or regular truck.
Do get some experience behind the wheel before driving off with an RV because they do require some driving experience.
However to rent RV's you need to be at least 21 years of age but to drive your own RV you can drive the RV at age 17 to 18 years of age.