If I understood you right, Lisp was not directly inspired by lambda calculus, but from McCarthy's own research into recursive functions where he found that the three primary functions can cover the whole of computation.

What I'm extrapolating from this is that McCarthy's ideas are similar in implication to Lambda Calculus where you can define computation with just function abstraction and application, and use Peano numbers to represent data. Both approaches end up creating a purely functional way to write programs.

Would that be correct? I also wonder whether there is anything we can take away from this knowledge that is applicable to programming or how we look at it?