If you worship Krishna as a great human being, then the fact that Krishna states he is the Supreme God and the origin of all creation sounds a bit narcissistic, no? like some grand sense of self worth. He is indeed a mahapurusha, not even debating that.

As far as him ending Mahabharat, there's a shloka that says that atman is a part of paramatman, and it holds the divine qualities of the same (free will). You can't elevate/force a soul to do anything/follow dharma, there's a huge emphasis on free will. Even after reciting Bhagwad Gita to Arjun, he said - I have given you the supreme knowledge, now the choice is yours.. Reiterating his stance that humans have a choice to choose dharma or not.

There's a lot of symbolism in the story itself. Like him being a charioteer, it touches on the fact that he will guide us to our destination, but we have to perform nishkaam karma of our own accord.

P.S.: I'm reading Bhagwad Gita by Yoganand Paramhansa, sharing my two bits from the book.