There's a lot to say of us incompetents
Competence is a concept.
We can be competent about some things and incompetent about others.
You can find people who are competent in many areas of computer science, it would be unpleasant to find one who is incompetent on everything.
The concept is that you should offer the services you are able to perform so as not to embarrass the customer or whoever has to correct the damage afterwards.
Then each of us can acquire skills to offer more services tomorrow. In the meantime, it is better not to boast of skills and competences.
I have often given up on jobs that I thought I was unable to do. Then a short time later I tried to make them for myself, to experiment and acquire skills and in fact I succeeded.
But I'm glad I didn't experience the customer's money firsthand, also because I would only have jeopardized my reputation for reliability.