Meaning of the sentence?

Hi, everyone.

Would someone tell me what the sentence in bold in the para below means?

As the plays became more and more popular, and as each dramatic tableau became more elaborate, the churcyard replaced the church itself as a theatre. Soon there were too many perfomers for them to be all clerics, and as lay people came to take part, so the native language and the humour of laity insisted on creeping in.

Thanks!