Most historical movements, unlike scientific discoveries and inventions, are the consequences or reactions. Someone spearheads them.
In some cases they deliver something extremely useful for posterity to cherish and in some they become an unending curse for humanity.
Adi Sankara was such a great person that even to understand all that is written by him and about him is beyond the wit of ordinary mortals. But what he delivered was the greatest boon to the world wherein he openly unearthed the fact that everything needed to be argued and debated philosophically, explained rationally and executed reverentially and anyone had a right to doubt and to question.
He bequeathed to the Western world that religious life includes all of the above and does not or need not constrain itself to one particular or any particular version.
Ultimately, Advaita is self explanatory philosophy showing that everything outside life is 'a way of life' which one has to merely learn to live.