Comment by Gravityloss

Apollo is not entirely a good model of how it should be done now. We don't do computer services the same way SAGE or SABRE were done in the sixties either. We should try to use off the shelf solutions where appropriate. But at the same time recognize where we need bespoke solutions.

Apollo had to do so much new things because there was no commercial space sector yet. You have now. Apollo developed engines and rockets and entirely new ways of operation. It would be a mistake to expect to develop an entirely new launcher rocket engine for example just for landing people on the moon.

For example, one could use multiple SpaceX Falcon 9 launches to launch and fuel a low earth orbit vehicle that would fly to the moon and send a lander. Most of the mass in LEO would be liquid oxygen.

There were alternative plans to use LEO assembly already in Apollo but it was deemed too risky. They did end up using docking after the translunar injection (turning the CSM around) and then of course famously in lunar orbit.

So you wouldn't need any new launchers to go back to the moon if one started a project today with a short deadline.