The moon has about the same make up as the Earth when it comes to distribution of elements in the crust. If it's anywhere near 8% like Earth then it makes sense to mine aluminum and other metals on the moon in order to build megastructures in orbit. Since the moon has no atmosphere you can accelerate things using mechanical mass drivers. Basically rail systems. At 5,300 mph you hit escape velocity and can then move payload somewhere with no rockets. It would keep us from polluting Earth too. This is the precursor to O'Neil cylinder type structures. AI robots will probably be the play but you still want a transportation system that works and frankly building a landing zone would improve overall outcomes regardless.

The rocks at the surface of the Moon are richer in metals than the crust of the Earth. They are especially richer in iron and titanium.

Without oxidizing air, it is easier to extract metals from the Moon rocks.

There is little doubt that it would be possible to build big spaceships on the Moon.

However, what is missing on the Moon is fuel. For interplanetary spacecraft, nuclear reactors would be preferable anyway, which could be assembled there from parts shipped from Earth, but for propulsion those still need a large amount of some working gas,to be heated and ejected.

It remains to be seen if there is any useful amount of water at the poles, but I doubt that there is enough for a long term exploitation.