Dutch has a separate history going back almost 1800 years after its initial split from Proto-German, and a singular Bible translation in the 16th century helped settle it into its modern form.
The most interesting part of the Dutch Story to non-linguists is the fact that English, German, and Dutch all sprang from the same ancestor, Proto-German. While many folks can get their heads around the idea that Dutch and German are related somehow, due to their similar spelling and pronunciation, linking English to Dutch seems like a stretch. But at some point prior to the 5th century, there was no English or Dutch, but just Proto-German.
By the year 450 there was a language known as Old Frankish, which experienced a consonant shift that split it into several sub-dialects, one of which was Old Low Franconian – also known as Old Dutch. In the beginning these languages were very similar, but slowly began drifting apart. Dutch slowly evolved until by the 12th century it had become what’s known as Middle Dutch. Middle Dutch was made up of five distinct dialects - West Flemish, East Flemish and Zealandic, Brabantian, Hollandic, Limburgish and Low Saxon. The people speaking these dialects could somewhat understand each other.
In the 16th century there began an effort to standardised Middle Dutch, after Spain conquered Antwerp and sent refugees streaming into Holland. All of these “versions” of Dutch were troublesome, and so a movement began to bring everyone’s pronunciation and grammar under one tent, so to speak. At the same time, the first Dutch translation of the Bible was introduced. This high quality translation, importantly, tried to be a version of Dutch that everyone could understand no matter their dialectal background. It also adopted the Latin alphabet, which helped in making Dutch spelling more consistent. Printed books were essential in the standardisation of many languages, as people around the area were exposed simultaneously to one way of spelling and writing a language.
In the modern world, Dutch has three main branches: Netherlands Dutch, Flanders Dutch, and Brussels Dutch. Additionally you have outliers like Polders Dutch (which differs mainly in pronunciation of dipthongs), Pennsylvania Dutch, and Afrikaans. More than twenty-million people in the world speak some version of Dutch, and while someone from the year 450 wouldn’t recognize any of it – it’s all related, and that, in my opinion, is amazing.