The items I'm listing here are just a subset of the critical path, and each milestone along the way will take months, optimistically, and years more realistically. To the point that starship won't be relevant to moon missions or any commercial use by the time it does what it needs to do to even partially fulfill the plans for it:
It needs to meet payload specifications. Currently it is off by a factor of two, which sounds doable until you realize the spec is 100 tons, and they need to find 50 tons more capacity by shedding weight elsewhere in the system.
It needs a launch cadence fast enough so that refueling doesn't take 15 separate starship tankers. Currently it would take years to refuel one single starship to make a one-way trip to the moon.
There's just a minor milestone on the way to that launch cadence: catching both stages.
Once both stages are reliably caught after a mission, refurbishment needs to be minimal. Proving that out will take several missions.
This is a simplified list of items on the critical path, but reaching each of these items has risks, and if those risks prove to be problems to solve, then each of those problems has a list of tasks and tests associated with it.
Some people think very highly of Elon for proposing technologically elegant solutions. But he's got a really big blind spot for the project management implications.