I'm not sure I understand that point you're trying to make. As someone who only speaks English, if English isn't a "single language" or "considered native", then what's my "native language"? My understanding of the term is that "native language" is descriptor of a speaker rather than a categorization of a language itself, so the idea that a language itself can be "not native" universally doesn't make much sense to me. I understand that different parts of English have roots in different languages, but from my perspective as a modern speaker with only limited knowledge of other languages (a few years of Spanish in school and then a few semesters of Dutch in college, but I'm not even proficient at a conversational level of either at this point), the origins of the words I'm using are irrelevant to whether I can think naturally in them; the fact I can check Google to see the entomology of the words "check" and "proficient" and see that one comes from French and the other from Latin doesn't affect my ability to understand them being used in this paragraph together. I strongly suspect that anyone else who identifies as a native English speaker would similarly be able to understand both of those words equally well, so it's not very plausible to me that there's no such thing as English as a "native language".