Human languagues developed as the need for communication between groups of people also arose. As these people settled, and interaction grew, the need for the use of words that would describe, and communicate, ideas, also grew.
Languages emerged given a great number of factors, but most specifically, the way that people sounded words, and used structures to communicate among one another. But as the world got larger, and contact between different regions of the world emerged through such activities as trading, contact between different languages also began, and therefore, adaptation of different words, from different languages, as people got in contact with languages different from their own. One major factor that influenced how one language affected another was the power that a nation, or a people, had over others. As such, if we look at such cases as Rome, we see that their Latin language, given their influence in so many regions of the world, and because they were the most powerful nation during their time, became the base for many other languages that formed, or developed later on.
As contact between people increased, and new languages were learned, and also as migrants established in another land, bringing with them their words and language, mixture happened and today we can say that at least in part, most languages have something in common.
English is no exception to this. Due to English being the most used language in the world, its influence on others has been enormous because people from other languages need to learn it, and adapt it to their own tongues. But the same applies to English. By having contact with people who speak so many other languages, English-speaking nations have also fallen into the adaptation of words in other languages that might better express an idea, than their own. This is the case of such words as lasagne, or tortilla, both words from different cultures, and different languages, but now incorporated into English as part of the language because the use of it through contact with those other languages has made it common and more acceptable than an original English version might.