Your understanding is generally correct. The technologies that enabled WW2 mobility (like tanks, aircraft, radios, and light machine guns) were too immature to allow the same level of mobility in WW1. The deadlock of WW1 stimulated the development of these mobility enhancing technologies.
In the century after Waterloo, almost all new military technologies favored the defense - rapid fire rifles, barbed wire, the telephone, quick firing artillery, smokeless gunpowder, railroads, etc. so that by WW1 the defense had gained a marked advantage over offense. The trend reversed after 1920 as most armies concentrated on developing new technologies and tactics for offensive warfare. France with their Maginot Line was the biggest exception. They stayed with defensive tech and tactics.
I would disagree and say that good old fashioned trucks were the most important or at least as important as armored formations. In WWI they could make holes, but could not move up troops fast enough to exploit the breach before the enemy concentrated defensive forces. Trucks, halftracks, top of tanks anything mobile allowed formations to exploit the hole and get into rear formations before the defense could solidify.