That’s an easy one - no. You can look back to various periods during middle ages Europe for examples. An even stronger one would be China from about 400 CE-800 CE
Of course, those weren’t capitalist economies - but they were economies. Capitalism’s instability is what requires constant growth to maintain. The better (and harder) questions would be what to transition to that avoids the issues of feudalism and how to transition with a minimum of societal upheaval (violence and death).
Knowing the “average” is all well and good, but doesn’t give that clear a picture. Does anyone have a source for the the median age, or better yet an age distribution graph?