Here's why:
* Different branches of the Germanic language family: English belongs to the West Germanic branch, while German belongs to the High German branch. These branches diverged thousands of years ago, leading to separate grammatical systems.
* Influence of other languages: English has been heavily influenced by other languages, particularly Latin, French, and Scandinavian. This influence has shaped English grammar and vocabulary in ways that are distinct from German.
* Grammatical differences: English and German have distinct grammatical structures. For example, English uses word order to indicate subject and object, while German uses case endings.
* Historical development: The two languages have evolved differently over centuries, leading to distinct grammatical features.
Therefore, while English and German share a common ancestor, they are separate languages with distinct grammatical systems. Early English grammar was not based on German but rather on the evolution of Proto-Germanic and the influence of other languages.