Grammar rules in English can sometimes be debatable. There is no regulatory body that governs the English language and books may show a variety of different possibilities to one answer. Latin and Anglo-Norman French have altered many things in English. What's your take on this?
I think that you are correct. I have found expressions in English that we know what they mean in English, but they really gramatically sound crazy. Though often they are a direct translation of another language.
English is a mix of North Germanic, West Germanic and Romance languages.
Although English is generally described as a West Germanic language (although some linguists at the University of Oslo claim it's really a North Germanic language: https://www.apollon.uio.no/english/articles/2012/4-english-scandinavian.html), this hybridisation means that there really isn't a language similar to English the same way Dutch and German, or French and Italian, are. You can figure out a surprising amount of Dutch or Norwegian words using just your knowledge of English and the context (I haven't been able to do this with French though), but there are too many differences to be able to do more than vague guesswork without starting learn the language. It's still easier than figuring out Old English though. Good luck reading Beowulf without knowing Old English :D http://www.fordham.edu/Halsall/basis/beowulf-oe.asp
You make a good point JMAT, English has been "de-germanized" so much that it stands on its own, although I was quite impressed with how much Basic Dutch and Basic English do resemble themselves. The Anglican tribes did have some contact with what is now present day Denmark, that could explain some North Germanic influence to some extent.
MEWE, you are right the language can get quite wild with grammar!