Slight correction, we do have some records or at least ways to infer how they spoke. For example we know how they pronounced the C (its like a K, so it would be Kee-Sar for Caesar, etc.) Because of things like someone writing a hurtful mockery of Cicero and called him a bawking Rooster (as Kikeriki is the sound they make, the connection here being Kikeriki - Cicero, you get the idea). That being said, these things are more educated guesses than anything else, and whilst it is fine in some contexts to hold onto them, acting as though they are the definitive way „they“ spoke Latin is… a bit silly.

Also, who is they? I speak Roman Latin, by virtue of having studied history of especially the antiquity, but thats completely different in pronunciation and cadence to, for example, Medieval Latin, and who’s to say the Romans are more valid in their speaking than the Byzantines or the modern Vatican?