[magissima]

"From Middle English -ish, -isch, from Old English -isċ (“-ish”, suffix), from Proto-Germanic -iskaz (“-ish”), from Proto-Indo-European -iskos."

https://en.wiktionary.org/wiki/-ish

[pessimizer]

Yeah, it's a little misleading to say that English borrowed that ending from German, English is a Germanic language and always had it.

[ncmncm]

Ok, and "-ish" and "-esque" clearly both trace back to the Proto-indo-european. So we're really just talking about spelling standards, which are a recent innovation.