I have segments AEP to Calafate and a return, which are both the LAST flights of the day. I booked it that way because I have a same-day arrival on MX at EZE and wanted a generous (5.5 hours) time between the EZE arrival and the AEP departure in case MX arrives late. The later Aerolineas flights were much cheaper, too.

So, if I'm at the airport (either AEP or Calafate) in time for an earlier flight, and there is space, does Aerolineas allow me to take it only by forfeiting the non-refundable later flight?

I understand later flights are often delayed, but are they canceled entirely?
Later the same day is not a problem, but "next-day" means losing the cost of the hotel room at the scheduled destination.