I may give my opinion from the perspective the other way round, so as a German who has learned English (to a somewhat useable extent). Note that this is highly subjective, though.
Personally I never considered English to be a difficult language, but I have been exposed to it from my early days on, especially through music and computer games. So I assume motivation plays a role here. What I noticed, though, is, that when it comes to vocabulary memorizing new words became easier when I grew older. This is for one part surely due to my already bigger vocabulary, increasing the chance that my brain could link a new word to an already known one (similar to how you get better at memorizing the 1∙1 the more of it you already know).
Another aspect imho is that due my academic education I came across a lot of rather academic vocabulary, which in German is usually of Latin origin. The same applies with all kind of technical terminology as well as computer related stuff (as mentioned, I am a gamer). So I would second that the similarity when it comes to germanic words probably isn’t that close, as even words of same origin have sometimes changed quiet a bit over time. But the common Latin word base appears rather big to me.
This might be a misinterpretation, though. After 30 years of dealing with the language it is probably hard to tell those things for sure. I most likely would have to go through my recent posts to really check how much of a percentage can be more or less transfered into German.
My perception is, though, that it is easier for a German to learn English than the other way round. For a German, when learning English I’d say the biggest hinderance is the rather irregular pronounciation. Even more considering that the language is spoken in different places in the world natively, and all of them have sort of their own English. Personally I find Japanese or Singaporean people easier to understand when they speak English than any native speaker. All L2 English speakers seem to speak more or less the same English, and all native speakers speak something else ![]()
When learning German, the grammar train hits you really hard, me thinks. And it appears to me, that people don’t enjoy learning grammar overall. I mean, many are already confused if the word order is different. So maybe it is also a matter of attitude? ![]()
Objectively, though, I don’t see why any language should be harder than another. At least among those used in the developed parts of the world. They all serve the same purpose. Of course, depending on who tries to learn which language. Strangely it seems that especially native English speakers tend to find German rather hard, despite the close relationship between those languages.