Ever since there were combustion engines for powering vehicles, these have needed gearboxes to transfer their torque, either as acceleration or as speed, onto the road surface. No, the very first gearboxes were not yet based on the gearwheel technology. Thus, by using a second pair of drive-belts, with a longer ratio, Carl Benz was able to make progress a little faster on smoother roads.
However, already Wilhelm Maybach had applied shiftable gearwheel-pairs to be able to choose the transmission ratio suited to the situation. Surprisingly, there was still a chain drive on the right and on the left to the rear axle. The drive shaft, an invention which is credited to Louis Renault, only appeared in the general vehicle construction later on. Thus, the coaxial transmission with direct drive (also from Renault) set the standard ever since the mounting of the engine up front in the beginning of the 20th century.
By the way, it was not always directly connected with the engine through the bell-housing, and by no means at the beginning of the vehicle gearbox technology. Even later than 1950 there was still a BMW (the 501), where the gearbox was mounted separately and connected to the engine by a small shaft. Later then, there were the 'transaxles', which were, sometimes with the clutch, mounted in front, or behind the rear axle.
The early gearboxes could easily be recognised by the noise that they made, quite often drowning the sound of, e.g., the large four-cylinder engines themselves. Added to this, was that the noises were by no means pleasant, as was sometimes the case with the engines. For a long time, the drivers were tormented with the procedure of shifting gears. Since, eg., the changing down by double de-clutching and giving only the right amount of gas, was not always crowned with success. If the procedure took too long, one could, eg., in a heavy truck, go directly into the next lower gear, which meant a further loss of speed.
Perhaps this explains, why cars with little sporting ambitions and also trucks from this period were fitted with rev-counters, namely, to be able to judge the double de-clutching process better. Driving schools spend a lot of time, teaching their charges how to (as quietly as possible) change gears. The dislike of the American buyers for manual gearboxes - which is still valid today -, may have originated from this period. Indeed, there was also another good argument for the introduction of automatic transmission after 1940, and that was to win the hearts of women as automobile buyers.
This started with a Hydramatic, which combined a hydraulic clutch with a two-speed planetary gearbox. A total of two speeds however, could only be implemented in the standard US-car, which at that time did not have the famous V-8 engine, but still had enough cubic capacity. In Europe the automatic transmission was only found much later, and at first, only in luxury class cars. Then, quite soon after, a torque converter was available, which kept the (subsequent) number of gears down at three-speeds for a long time.
Although slowly, the manual gearbox was also developing. Even though in 1928, Charles Kettering introduced the synchronised gearing for GM, the common gearbox survived almost solely in the Corvette, and even there, not totally. In Germany, ZF is considered to be the inventor in this area and was able to assert itself, even against the construction of Ferdinand Porsche. Of course, it was further developed, e.g., in the later years through multiple synchronisation in the lower gears.