My reply to you was regarding ‘Islam hasn’t changed’.
The letters in the book are the same that’s true. But people rely on translation and tafsirs to read the letters, all of which are completely different from what the contemporary scholars wrote. This is why I feel that scholars still hold a lot of power to mould Islam to whatever suits their interests. Although most of the recent translation changes are an attempt to keep Quran some what upto date with latest scientific discoveries.
Other than Quran you will find that most modern Muslims dispute authenticity of Prophets biography and even certain Sahih Hadith, both of which are cornerstone of contemporary Islam and second important sources after Quran.
Changing translations and tafsirs of Quran. Discrediting and ignoring Sahih Hadith which were unquestioned sources of contemporary Islam is an attempt to change the religion. That’s why I said the practises and beliefs of Muslims from 1400 years ago is completely different. If you can bring a Muslim from 1400 years ago and compare his beliefs with a Muslim from today’s mainstream Islam, the two religions would be so different that you would need a new name to distinguish between them and classify them.
Quran hasn't changed, but you are talking about interpertation (Tahweel).