In 'the singles party' the noun 'singles' acts as attributive noun modifying 'party'.

There is an English proper adjective 'German', as in 'German people', deriving from the toponym 'Germany'.

Finally, we have the proper noun 'German' in the sense of 'German language in general'.

Here's my question: In 'the German alphabet', is 'German' to be interpreted as i) the proper adjective 'German' ii) the proper noun 'German' (the language, not, e.g. German citizen), acting as attributive noun modifying 'alphabet' or iii) one or the other; both interpretations are grammatical, maybe different semantics ?