English or English's ?

Before attending English101 I knew their where different types of English's and I would define it as plural. In my mind I had a sense that meant the languages everyone uses around the world. For example, American and British English is different. Yes, most of the words we use are the same as hello, no, stop, or car. But there are some words we people in The United States don't understand or we wouldn't communicate to other people in some of the ways they communicate in Great Britian. Even the spelling of the same words of English we use are different. In America we spell center as "center" and Britian spell center as "Centre". My definition of "English" has changed throughout the class, at first, I knew English was a language that was spoken around the world. After learning the type of ways, we communicate with people in different types of situations. I've gotten a more in depth of understanding of the difference between informal and formal English.  What I've noticed to be difficult to understand global English's is how different parts of the world evolved to speak multiple types of English's. I know because the world is so large, we grow to make our own languages, but English being one of the most spoken languages on the planet, I've always wondered why they couldn't just all make One English. Of course, including the slang and informal words. In all, I want to learn more about the different types of languages that are in the world. I feel like we haven't discovered some, or words people around the world use but we don't know about. I also want to learn how people communicate and when do they deforciant between the types of English's in multiple occasions. Being able to have the knowledge pf the types of English's will help you be able to communicate and navigate throughout your life.