Having returned to the church, Zheng Yichen felt refreshed and reassured to know that his bodily structures were all normal, and that he basically wouldn't undergo any additional anomalies; he wouldn't have to worry about something bursting out of his body like those small animals do.
Of course, once he became more powerful, he could get re-examined somewhere else. Previously, his aversion to physical examinations stemmed from his fear of being taken away for research. Once his strength improved, he wouldn't have to worry about this issue.
When Extraordinary Beings initially emerged, as long as one subjectively considered themselves human, there would be no internal or external changes. When his anomaly appeared, he was still in the dark about it.