I'm spending the next two weeks traveling through Peru, and seeing a bunch of Spanish signs made me think: why do all of these seemingly unrelated languages share the same alphabet? A lot of them probably have developed independently, and I cant see why they'd all use the same alphabet.
These languages all use the Latin alphabet, which is derived from what was used to write ancient Latin, though it has gone through modifications over the centuries.
I'll come back with more when I'm not on mobile, but reading up on the history of the Latin alphabet meanwhile will explain how it became used in the Romance languages, German (see especially Gothic script), etc.