I have a number of thoughts on this topic. For one, does it matter if the teacher existed in the way our stories say? Or are the teachings important? I guess this depends on one's perspective.
For example, can Christians find meaning in a Christianity with no historic Jesus or resurrection? Does the Mormon church fall apart if Joseph Smith wrote the Book of Mormon and there were no golden plates or guiding angel? Does the Torah stand if there was no Moses?
In turn, what if the Buddha is merely a legendary amalgam of different people and their teachings? Can Buddhism survive on its message if there is no clear messenger?
To this question, my personal answer is yes as a Buddhist. After 2500 years, it is challenging to separate myth and history regarding Gautama Siddhartha. For me, the practice and teachings are what I find helpful and of importance. I would certainly like there to have been this one genius Buddha who expounded these teachings and served as a role model. Nevertheless, my belief system does not require a Buddha anymore than I need to know the essence of Italian cooking was developed by one incredible chef to be able to take delight in Italian cuisine. The recipes live on and develop. I suspect Buddhism similarly developed. And if there was a historic Gautama Siddhartha, I suspect he would want us to focus on the practice.
