The answer to all of your questions is no.
The name "England" derives from the Old English name Englaland, which means "Land of the Angles". It is worth noting that, in the context of language, Old English is a synonym for Anglo Saxon. (The earliest recorded use of the term that I'm aware of is in the late ninth century translation into Old English of Bede's Ecclesiastical History of the English People, which had been written in Latin in in the early eighth century.)
The first "King of England" was Ecgherht (Egbert), who ruled from 827 – 839. His actual Anglo-Saxon title was Bretwalda (“ruler of the British”), rather than King, but it meant broadly the same thing. There was no entity called "England" before that.
Egbert was almost certainly descended from Germanic invaders who arrived in the early post-Roman period, but probably also from native Romano-British peoples. The truth is that we lack the evidence to be at all precise about his ancestry. By this stage, the "English" people were, by-and-large probably a mixture of these peoples. Not German, not Romano-British, but - for want of a better word - "English".
So, the answer to your first question is no. By the time there was an "England", the people who ruled there were no longer "German".
For your second, third and fourth questions, the answer is also no. If you look at the Wikipedia page for the History of English, you will see that the Old English (a.k.a "Anglo Saxon" - see above) of Beowulf, developed into the Middle English of Chaucer, which in turn became the early modern English of Shakespeare, which eventually became modern English (and, via Webster et al., American).
The language was never lost, and so never needed a statesman to champion its cause.
For question 5, see question 1.