It seems like most languages wouldn't require you to learn to pronounce new sounds, that most of the sounds used are similar to those used in other languages, only a minor difference in accent.
Like the rolling r in Spanish (though Spanish is very similar to English anyway) is a new sound, but most of the rest of the letters are easily pronounceable.
More a question for linguists (see: articulatory phonetics). You might be surprised how different some languages can be.
The basic answer, which I wont bother supporting since its not a historical question, is that human biology is more universal than culture. We have common vocalization mechanisms - it is not strange that the easier-to-make sounds are more commonly deployed (those made with teeth, lips, and roof of mouth, in particular).
This does not mean that you wont be required to learn new sounds, depending on the language being learned - for instance, English does not use uvular noises, which are commonly used in Arabic.