Short answers, pulled from the story.
Direct ascent is a method of landing a spacecraft on the Moon or another planetary surface directly without first assembling the vehicle in Earth orbit. NASA initially planned the Apollo program based on this assumption using either the Saturn C-8 or Nova rocket to launch the three-man Apollo spacecraft.
NASA abandoned direct ascent because it required developing a prohibitively large launch vehicle that existing technology could not support. The size constraints made the original plan impossible to execute so engineers chose alternatives like Lunar Orbit Rendezvous instead.
The Soviets attempted to launch the N1 rocket on the 21st of February 1969 and again on the 3rd of July 1969 but both launches failed completely. Two more attempts occurred in 1972 and 1974 but neither succeeded while NASA's Apollo 11 lifted off and made the first crewed lunar landing on the 20th of July 1969.
Engineers designed specific rockets including the Saturn C-8 and the Nova rocket to carry entire crews without orbital assembly. The Soviet Union developed the UR-700 modular booster for their own efforts while no other nations pursued such large-scale single-launch strategies during this era.
Science fiction movies frequently depicted direct ascent missions with films like Rocketship X-M showing a two-stage vehicle that accidentally landed on Mars and Destination Moon featuring a single-stage vehicle which successfully landed on the Moon. These cinematic depictions often ignored the immense size constraints required for success while real engineers struggled to implement these concepts.