Jan Vansina studied people in Central Africa. Do you have any scholarly rebuttal to the specific people we are talking about in the1st century Jerusalem?Irrelevant. Jan Vansina has studied oral traditions in Africa, which as you have stated, were also prevalent in 1st century Jerusalem. You cannot arbitrarily exclude him because his field of study is contemporary oral traditions rather than historical ones.
Is this your opinion or fact? Can you cite references please?