Spanish patatas bravas are potatoes served with a red sauce made with tomatoes and chilis. Could patatas bravas have existed in 1490?

No, patatas bravas could not have existed in 1490. This is because in 1490 the Americas had not yet been visited by Europeans, and so Spaniards didn't have access to the potatoes, tomatoes or chilis present in the dish, because those plants are all from the Americas originally.