Is English a flexible language in word choice?

By word choice I mean a range of words or expressions you can choose from when writing, speaking.

I felt this way because however much I spend time reading books or writings on the Internet written by native speakers of English,
I don’t really get a feeling that they are speaking in the same language, or get the hang of English in general.

Each individual’s linguistic style differs so much so that I almost feel like they are speaking in different languages.

And so many words are adaptable to so many cases that I feel like each word in English has more uses than I realize, or no limited use at all.

If you can relate to this writing, than perhaps I could be right.
If you can’t, it all happens just because I’m standing on a standpoint of a foreigner whose first language is not English.