English not being standardised because England hasn't been invaded since 1066 feels like a red herring, maybe this is part of a greater argument with more context but I'm just completely missing what relevance this has at all.

English not being standardised because there's no central authority is an easily acceptable proposition, although in defence of English it's hard to standardised a language when it's being spoken by independent industrious nations on entirely different continents. Had French remained the lingua franca or had Spanish overtaken both English and French we'd be having the exact same conversation about how those languages never underwent standardisation like English would have done in this alternate history.

Something to remember about standardisation that you yourself also noted is that German, and indeed most languages that have been reformed and standardised, did so fairly recently and require regular standardisation attempts to reflect the ever changing nature of language. Dutch, French, and German all underwent unification/standardisation around the 18-19th century as well as introduction of spelling reforms in the 1990s. Brazil and Portugal both had two reforms in the 20th century. Norway has had half a dozen reforms since the start of the 20th century. Even non-European languages like Japanese and Chinese have reformed since WW2. Spanish did successfully reform in the 18-19th century but has mostly remained the same, possibly for the same reasons that would make a modern English language reform difficult.

As far as English being difficult to learn, there are many aspects to consider when it comes to difficulty of language but spelling seems so far down on the list that it's barely worth considering. Sure, there are an obnoxious amount of spelling rules being stated as fact that happen to have more exceptions than the rule covers, and it's awkward not knowing how to spell a word after hearing it or being able to pronounce a word after reading it, but there's no radically different regional dialects to learn (despite being unstandardised) like in German. French is standardised but it has a complex (albeit consistent) spelling system that's based on etymology rather than phonology. There's no complicated grammatical gender system to learn, there's no real complex grammar like Finnish or grammar with exceptions like Russian, the phonology is fairly simple and pronunciation isn't too difficult or strict, etc. The main complaints about English from non-native speakers seems to be that spelling and pronunciation is inconsistent, which is something native speakers struggle with, it just doesn't seem like that big of a deal in the grand scheme of things.

- ramblings below -

>English isn't a "real" language.

I'm really struggling to understand what you mean by this. A generous interpretation would be that English isn't a continuation of the language that has been spoke on Britain, which is clearly true, but you go on to say that it has a bunch of French and Latin words (30% and 30% of total vocabulary respectively). By this metric is French a real language? 20% of French vocabulary comes from German and Greek. The same can be said of German which is 20% French and Latin. How about Portuguese which has 25% of its Vocabulary coming from English/Arabic/French/Latin/etc. Up until around the 19th century written Norwegian was simply Danish, and even today there's a struggle between Bokmål and Nynorsk, is Norwegian a 'real' language?

>English started as old German (Angols and Saxons brought it over).

While you didn't explicitly say that English comes from Old German it's worth pointing out that there was no specific Old German for English to have come from. Old English during the migratory period (more recently but disputedly referred to as the Anglo-Frisian language or dialect groups) would have been extremely similar to the language/dialects that the Angles, Frisians, and Saxons spoke, and this lineage can still be seen today with Frisian followed by Dutch being the most closely related languages to English. Documented examples of written Old English even predate those for Old Saxon (or Old Low German) by a good 100-150 years, so while English is a Germanic language it's not necessarily something that just existed in the same form prior to the migratory period.

>And the grammar got massively simplified.

This was never something that happened from a singular event in a singular place, for example Old English started to lose grammatical gender around the time of the Norse invasions but Danelaw had a big effect on its decline, however in more conservative areas of the country grammatical gender would remain until the 13th century, that's a good 400-500 years that covers both Norse and Norman conquests as well as the Old English to Middle English phase.

It's also worth noting that simplification of grammar is something that tends to happen to most languages that have contact with a large degree of adult settlers that are attempting to communicate with you, something like grammatical gender is difficult to learn as an adult, this simplification isn't something that makes a language 'less real'.

When it's the case of the entire aristocracy or ruling class being replaced (as is the case during the migratory period or the Norman invasion) this step tends to be skipped as no attempt to learn the common language is made, instead the common language is replaced entirely (as was the case with the Romano-Celtic language spoke in lowland England) or the common language inherits vocabulary (as was the case for the Norman invasion). A good demonstration of this is the decline of the Cornish language that was accelerated by English replacing Latin as the language of the church.

>Both these factors are to suit the invaders for instance cow is from the German Kuh, because peasants keep the cows. But Beef is from the French Boeuf because aristocrats eat the cows so they use the French word.

We do use the French word 'beef' and it's commonly attributed to the Norman invasion but the same separation of finished products that the aristocracy could afford and unfinished products that the peasants would produce exists in other languages too, 'cow' in French isn't 'boeuf' but 'vache', kuh/rindfleisch, carne de res/vaca, etc.