Does this particular tense(historic past) only retain to things that are like centuries ago? Because I've seen a few sentences that are probably about things that happened recently, i.e. this one
It depends on where you are in Italy. The farther south you go, the more likely you are to hear them using this tense in speech to refer to recent events. But outside of those regions, this tense is only used in literature. In non-fiction, it generally refers to events from a very long time ago, but I believe it's a little more flexible in fiction.
The main thing is consistency. If a writer uses this tense for the simple past, then they will not mix in the present perfect to get the same meaning.
how did the conditional get into this? perhaps DL was thinking of "potremmo"