First of all, it is NOT evidence for Adam's historicity to point out that both Jesus and Paul spoke about Adam as if he were real. This is unfortunate, from one way of thinking. However, the pattern of Jesus and Paul IS an example of how we might speak and write about Adam. Thus, we might do as well as Jesus and Paul did if we continue speaking AS IF Adam were, in fact, a historical figure. (Was he? That's an important but unanswerable question. I'm saying, of necessity, we might do well to let these remain separate issues.)Read his post - Genesis AS IF History.
If you're following the conversation here about biblical references and historical characters, I'm still working on the follow up post about Daniel in Ezekiel 14. Anybody have access to Block's commentary and want to send me the pages where he deals with the question?