Neither Java, nor c#, are simple. They're arguable less complex than things like f# and scala, but its quite a lot about the question of familiarity.

If you're coming from an imperative, oop, background then these languages will require more learning because you're not familiar with the concepts.

But a language like Java is huge by comparison with something like Javascript or python. In terms of the size of grammar, the number of semantic rules required for description, etc.