I have no regrets that I didn't learn the pommel horse while I was still in my teens
Even that may not be closed off...I got hauled to adult tumbling classes for a couple years in my late 30's and while I never got very good, it was a lot of fun and improved my balance dramatically. I got as far as doing a front tuck on an extra springy floor. So even some pretty demanding physical things aren't out of the question. It also helped my crashing in bicycle races dramatically-- there's a lot of time to think in the air, and if you've had some practice you can reduce your chance of injury. Plus the gym was a pretty interesting scene after the kids left and the adults came for open tumbling-- it was mostly active stunt people and ex-gymnasts.