This is an exaggeration of the number of people guiding them, to emphasize the importance of the one spiritual father. AT: "very many guardians" or "a large crowd of guardians" (See: [[rc://en/ta/man/translate/figs-hyperbole]])
Paul is emphasizing firstly that his relationship with the Corinthians is most importantly "in Christ," secondly that it came because he told them the good news, and thirdly that he is the one who is like a father to them. "it was because God joined you to Christ when I told you the good news that I was the one who became your father"