Yep, by 1941 Germans had no idea about semi-auto rifle. They only caught an idea as they started to capture AVSs and SVTs from Russians. They had put captured Russian semi and full-autos into service before they reverse engineered it into various “Gewehrs” including Stg-44 which was a first original design, thus heavivy inspired by the Soviets with the exception of their unique shorter cartridge started an assault rifles as we know it.
Unfortunately, US has lagged behing both Germans and Russians for decades. M-14 is simply a conceptual copy of Soviet AVS-36 built 20 years earlier.
Schmeisser invented the M-18 submachine gun for WWI assault groups.
German, between the wars, focused on infantry using machine guns at long range, and assault groups with submachine guns at short range, with the rifle being a self defense mechanism for ammunition carriers. The K-98 was fine for that.
German squads had tremendous firepower. The firepower was highly concentrated in the few men who serviced the General purpose machine gun. The machine gun teams were less mobile, but the assault squads compensated.
US squads with BAR and M-1 had less firepower, but the firepower was better distributed. US MGs were specialized, with the .50 HMG having longer range than the Germans, the .30 MMG having better sustained fire, and the BAR having higher mobility.
UK squads with BREN and Enfield were intermediate between the two.
Soviets had fewer machineguns, but more PPSh armed assault squads, backed up with Rifle Infantry with Mosin Nagants.
The preferred approach to the German infantry used their predictability against them. One would attempt to shoot down the assault squads at long range, to attack the machine gun teams by using mobile assaults with suppressive fire, and to use high rates of fire against the few rifle armed ammunition carriers.
The STG-43 gave the Germans a weapon that would have longer range than a MP-40, higher rate of fire than Mauser 98K, and, better mobility than an MG-42. That made the Germans less predictable. Still they lost 18 to 1 when fighting US 2nd Infantry in the Bulge battles. M-1s with BARs and .30 Brownings are a pretty tough combination.