It's paper has been radiocarbon dated to earlier than Uthman, however only 2 scholars accept its radiocarbon dating as indicating precisely when the text was produced. Others leave the possibility open of it being produced earlier but date it likely to the time of Uthman according to my understanding.
For a complete summary of the views of academic historical critical scholars you can see this article here under the title "significance"
en.m.wikipedia.org
I have not included it all as many scholars have weighed in on the debate.
Anyway, this is irrelevant to authorship. You are bringing in a red herring you will hang onto and go on and on. It's a waste of time.
It's linguistics. This is a red herring or you have not read up on philology or other sciences of linguistic study like ilme maana as one example. Why don't you actually read my responses instead of handwaving?
Most scholars in the exact field of linguistics in this question have concluded that it was written by one person thinking of the topic in a naturalistic manner from my side.
If you read the text directly, the coherence of the text shows very easily that it was one writer. There are many routes to this factor. One is called "Adhab Mukaran" which is to study parallel texts which will show parallels with other existing texts and it's a show of how one text could have various sources. And even if you take the Qur'an as copied from other sources, it's still written by one person. A qualified philologist in the Qur'anic text will affirm that it was written by one person and in arabic the study is called failulujeeyyah. When you get into stylistic features, rhetorical techniques etc, the coherence shows that it was written by one author and the study is called allugaaweeyyah or/and usloob.
All of these scholarships may fall into the category of source criticism and form criticism.
I don't know if you would find good sources with a search like that on google or something. But I can recommend some books. This is not wide on google which I presume because it's not a topic discussed much unlike the Bible which directly quotes various authors.
Anyway, try and find a scholar called alJurjani who wrote on the coherence of the Quranic text. Or Ibn alAthir. Or maybe even Dr. Raymond Farin.
If you wish to read some additional text critical work, read Angelika Neuwirth although she is not a philologist or ilme maana. She is a textual critic. Her information would take you down a different route. They are all highly qualified in the field.