In what way can "Things Fall Apart" be considered a tragedy? In what way not?

A tragedy is defined as a story where the protagonist is unsuccessful. At the end of "Things Fall Apart", the protagonist, Okwonkwo kills himself because he cannot adapt to the changes in the Igbo people. He resents Christianity and the white man. However, in death, Okwonkwo becomes a hero and actually brings back some of the traditional Igbo ways. They will not bury his body because he commited suicide and they make sacrifices to cleanse the land desecrated by the suicide. His friend, Obierika exclaims that Okwonkwo was one of the greatest men of his tribe and it was the white man who drove him to kill himself. So, by killing himself, Okwonkwo brings back some of his people's traditions and makes them aware of the dark side of the white people. Okwonkwo is a tragic figure but his death brings back the very things he died for.