GCSEs mostly taken at 16 used to be called
ORDINARY levels passes are A thru C
The benchmark standard is 5 grade C or above
for many jobs - but this is a minimum
ADVANCED Levels mostly taken at 18 (grades A thru E) are what all the good UNIVERSITIES require for admission in the UK e.g Cambridge
People take at least 3 for admission to such places and typically get high grades i.e. AAA
Its possible = but not desirable to bipass the above in the UK, as employers refer back to this as a key performance indicator
How this relates to Germany I dont know