Who is John Jasper?
There is a very famous 20th century American painter named Jasper Johns. I have included a link about him below in case that is who you meant.
The only person named John Jasper that I have ever heard of was an African American preacher who lived in Richmond, Virginia. Jasper was born a slave and lived the first 50 years of his life as a slave. He preached as a slave and continued preaching after emancipation. After emancipation, he formed a free black congregation and built a church for it. The black church was very important in the days after emancipation. It was one of the main ways in which freed African Americans tried to build themselves a community in the face of white hostility. It is for this reason that people like John Jasper are important in American history.