“To teach is to learn twice.” – Joseph Joubert
You don’t need to be an expert to be a good teacher. In fact it often helps if you aren’t. Experts tend to gloss over a lot of details that beginners need to know. The reason for this is the experts are thinking at such a more advanced level that it never occurs to them to cover many things that seem very obvious.
An intermediate developer might be better at explaining a topic to a beginner than an expert.
You don’t need to be very much better than the next guy to be a good teacher.
You only need to be one step ahead to be able to explain the next step perfectly.