Actually Lisp uses ordinary old polish notation. Reverse Polish Notation is used by stack-oriented systems like HP calculators and Forth.
(- (+ 1 2 3 4 5) 1)
and
- + + + + 1 2 3 4 5 1
The first one seems much more readable to me...
And parentheses don’t serve precisely the same role in Lisp syntax than they in the more free-form world of maths.