Most people prefer their first language over others they learn later in life. My opinion is that Colombus learned how to read and write in Spanish. His Spanish was sort of a mishmash of Spanish, Italian and Latin. I have not read a lot of his writings, but what I have read do not impress me much. People in Barcelona did not and still do not speak Spanish, they speak Catalan. The books Colombus read about navigation and travel destinations were mostly written in Latin. His father was some sort of fabric merchant. I do not believe that he was Jewish or came from anywhere other than Genoa.
There was no Italian language in Colombus' time. There were an assortment of dialects that later became standardized as Italian, based on the Piedmont area dialect somewhat later. Colombus would have spoken Genovese, which is not precisely Italian. Spanish became standardized as Castillano about the time of Colombus. Isabel was from Casilla, Ferdinand was from Aragon, which included Catalonia at the time. Aragon was divided linguistically between Aragonese, much closer to Castillian, and Catalan, which was and is the language spoken in the Baleric Islands (Mallorca. Menorca, Ibiza, Fomentera and some smaller islands), as well as Andorra.
