Without railroads and highways, Afghanistan will never move forward. It should have been the first thing we did, and not only to link up cities, but to locations with large amounts of natural resources to build up some wealth and industry.
Such high illiteracy rates will make it impossible to build enough of management and general bureaucracy needed to build anything large. It will make it hard to train workers in technology. You won't build railroads nor roads, you won't mainten them either.
Primitive mines are not competitive. They are not producing enough to feed you. And hungry people won't save money for school. You need technology.
20 years? Zahir Shah tried this for 40 years. Amanullah Khan also tried, as did several others. Numerous would-be reformers have thought as you do and tried to impose change on Afghanistan, and all their efforts have culminated in the situation we have now. It's been approached from a number of ideological/political directions. Some were monarchs, others proponents of republics. The PDPA/Soviets tried it from a Marxist/Leninist angle with lots of bloodshed, while Zahir Shah tried to create a constitutional monarchy and refrained from murdering his political opponents. Neither succeeded in the end.
What would you bring to the table that hasn't been tried before?
If the US had spent the last 20 years building infrastructure, railroads, highways, mining operations, schools to train engineers, managers, and professionals, Afghanistan would likely look a lot different.
But the US missed even low hanging fruit like making poppies a legitimate crop by giving Afghanistan a cut of the legal opioid market.