Firstly, thanks for the flowers. I'll be back tomorrow to collect my pot ;op
No, this are not neutral gender nouns. If it is for males it ends with an "O", if it is for females it ends with an "A". For Example Isleño/Isleña, Jarocho/Jarocha
About the the Salvadoran forms. A guanaco is a large mammal that lives in South America
and is related to the llama. It is bigger than a llama and not domesticated. They mainly eat grass and live in the mountains. I have NO IDEA why it is that they got the nickname "Guanaco" at El Salvador
. Maybe because of resemblance...? (kidding)
As for Chero, Salvadorans call each other "chero" or "Chera" (depending on gender). Chero means "pal", "body". I don't have the etymology of the word Chero, Sorry.
About Cuba, Isleño translates literally into "from the island". Something like "Islander"... And Guajiro is Cuban slang for "peasant", so they are both accurate in "nicknaming" a Cuban.
As for Carioca, I'm sure it is what Brazilians call people from Rio
de Janeiro. It is just that perhaps, the rest of the world is not about to make distinctions, so a Carioca is a person from Brazil, to the rest of us.
And about Jarochos, I must admit I was WRONG. They are from Veracruz and NOT from Jalisco.
You are welcome,