When I was at Buffalo 30 years ago, Tony Ralston advocated teaching discrete math instead of calculus to 1st year students. I taught it out of some notes he had prepared, and thought the students found it harder than calculus. It was easier to relate calculus topics to things they already knew about than it was to do that for the topics in his notes.

I'm pretty sure those notes became a textbook, so you can probably get a copy and see one man's idea of what should/could be taught to students before calculus.