Of course they could.
Napoleon left an extensive record. His opponents left an extensive record. His generals wrote. His inspector general of bridges left behind one of the greatest graphs of all time.
Julius Caesar left behind a book, written by himself. Augustus had various courtiers who wrote about him and his family. They were deified after death, and left much behind to include various statues and buildings, and the rostrum in the Forum. I decline to judge the nature of the divinity that was bestowed by men upon other mean, but that is what real events look like.
Jesus: no evidence of anyone writing about him for years after his death. He never seems to have written anything. Yet his followers make the greatest claims on the basis of nearly no contemporary evidence. Fraud
Mohammed’s followers conquered much, and after that developed the Qu’ran and Hadith to justify themselves. Another mismash of conflicting fables. The late authoring of the Qu’ran and its single version are explained not by fraud, but rather by the assertion that hundreds of people memorizing what Mohammed said, even when he was a small town bandit. Fraud.
John Smith invented books from whole cloth that differed from all the archeological evidence, by claiming magical translation. Fraud.
Great claims require great evidence. Meet the standard of evidence for Caesar, and perhaps we can talk.
Julius Caesar left behind a book, written by himself.
***Earliest extant copies (7 of them) were written 800 years after his death.
Jesus: no evidence of anyone writing about him for years after his death.
***Many accounts were written of Jesus, most of which were before AD70. That’s only about 40 years after his death, not 800 — and there are 17,000 manuscripts of the new testament, far far more than Julius Caesar’s stuff.
You have idealogical blinders on, and not one figure of history can stand up to it. The standard you set up for Caesar is completely trounced by Jesus of Nazareth.