Robert Strimple is Professor Emeritus of Systematic Theology at Westminster Seminary in California. Interestingly, he did his doctoral studies at Trinity College, University of Toronto and taught for a time at what is now called Tyndale University College in Toronto.
Strimple recently wrote a piece for the Westminster website called “Was Adam Historical?” where he takes a more theological look at the question. He pays particular attention to the neo-orthodox understanding of Adam as non-historical but theologically significant, as in Karl Barth or Emil Brunner. This is quite useful. His final paragraph says:
To conclude: Our understanding of the reality of Adam affects our understanding of sin, of redemption, and of the Redeemer. The one who rejects the Biblical teaching regarding the historical Adam and the historical Fall will find no firm basis for accepting the Biblical teaching regarding the historical, Incarnate Redeemer.