What exonerates Bach's music from being assessed by the same modern criteria? What if, what was, back then, known as "composing music" was what we would now, ho

What exonerates Bach's music from being assessed by the same modern criteria? What if, what was, back then, known as "composing music" was what we would now, honestly, describe as a laughably narcissistic activity, comparable to Thomas Heatherwick's designs for London buses or the Garden Bridge. The question is not of the status (culturally) of the work, but of its originality. The measure is of invention vs mere elaboration, or concept vs substantial process.