Huge mountain ranges separating people that are close in distance is a pretty classic mechanism of creating linguistic diversity / dialects in places that are physically close to each other. You see this with villages in various parts of Asia historically.
Indigenous language effecting Spanish is something that would effect everyone in South America, so even if you remove Spain from the table, Colombia, Chile, the Caribbean and Costa Rica will all stand out about how "different" they are from the rest of South America, probably from their physical barriers separating them from the rest of the continent.
Indigenous language effecting Spanish is something that would effect everyone in South America, so even if you remove Spain from the table, Colombia, Chile, the Caribbean and Costa Rica will all stand out about how "different" they are from the rest of South America, probably from their physical barriers separating them from the rest of the continent.