I have my father's original birth certificate and his marriage certificate from Italy. However, the consulate website states:

All documentation must be submitted in original and will not be returned (with the exception
of the naturalization certificate)

I do not want to lose my copies of his ...

I saw on the consulate website that we do not get the documents back. Is that accurate? Is it possible to get official copies?

You would be tracing your citizenship through your mother, but first you would have to demonstrate she was indeed a citizen. This means showing proof of your father's citenship and naturalization PLUS the marriage certificate demonstrating the marriage took place before naturalization.

It's ...

According to Italian law, naturalization ended Italian citizenship so that would disqualify you from applying though his line.

However, if your parents married before he naturalized, your mother automatically acquired Italian citizenship at that time, and she was not affected by his ...

My father was an Italian citizen born in 1915. He emigrated to the US and was naturalized in 1947 by marriage, but he did not renounce his Italian citizenship. I was born in 1952. Does his naturalization prior to my birth disqualify me from citizenship by iure sanguinis?