Wings was mediocre imo. Solo career success for members of band like the beatles is a given, they have the biggest fan base in the world for the most part.
The creativity also comes from the new band members and the style etc.
It's not that the beatles stopped being creative, they couldn't stand to be around each other in the end and that's what soured the longevity.
They were each doing and wanting to do solo stuff whilst still in the beatles and often wanted to record their own songs alone. 10 years is about it.