The book “Ignition!” explains the realities of chemical rockets. The Saturn V is as powerful as it gets, given chemistry and the rocket equation. Modern construction techniques and computers can bring the costs & overheads down, but they can’t make hypergolics better.

It's true we're all working in the margins of efficiency, but that's like saying there's no difference between a Falcon 1 and Starship. Saturn V isn't close to the limits of how big you can make a rocket, nor how efficiently you can make a rocket, nor how cheaply you can fly a rocket for. There have been plenty of proposals along the way for bigger, cheaper, more modular, and more reusable spacecraft, plenty of which are totally compatible with historic methods. Even literally “keep flying Saturn V” would have been better than what we did.