I think it’s important to realize that you were not hired with the expectation of you being the best at what you do.
Companies have one simple requirement, get the job done. Excelling at what you do is definitely important and is the basis for career growth, but is not necessarily a requirement for job security.
I once asked the father of one of my friends for career advice. He himself is an established leader and a very successful CEO. His answer to me was simple: try to finish all of your work everyday. As simple as that sounds, as difficult as it is, and as humbling as it may be that the basic requirement is getting the task done at a “satisfactory” level of quality.