First, no modern translation says "no man". That is antiquated KJV language which you are dishonestly mixing with modern English to make it appear that that no human understands. The Greek word is
oudeis, and it is translated "no one".
Strongs Concordance
oudeis and outheis, oudemia, ouden and outhen: no one, none
Original Word: οὐδείς, οὐδεμία, οὐδέν
Part of Speech: Adjective
Transliteration: oudeis and outheis, oudemia, ouden and outhen
Phonetic Spelling: (oo-dice')
Definition: no one, none
Usage: no one, none, nothing.
Now "no one" does not necessary mean no one in the whole world. The scope is determined by the context. To see what I mean let's look at a couple of other examples of that word elsewhere in scripture. For instance the same word appears in Mat 22:46
"and from that day on no one dared to ask him any more questions". That doesn't mean no one in the whole world dared ask Jesus any more questions, but rather the Pharisees whom the context is referring to. Similarly in Mark 5:4
"No one was strong enough to subdue him". That doesn't mean the demon possessed man of the Gadarenes was the strongest human that ever lived. It means no one in the local vicinity was strong enough to restrain him. The context determines the scope. And the context of 1 Cor 14 is local church meetings.