It should be recognised that the German eastern front during the great war was fairly mobile, therefore it cannot be simply argued that technology or tactics were the reasons for the stalemate and attritional warfare of the western front during the great war.
Indeed many commanders began the great war under the impression of a swift mobile conflict, therefore here too we see that the prevailing Zeitgeist of the times does not in itself explain events that transpired.
To look back at development of military doctrine it could be argued that the Napoleonic Wars developed the concepts of Massed Artillery, and the American Civil war and Prussian wars developed the concepts of a war of manoeuvre that would underpin the ideals as the great powers began WW2. On the one hand the power of the artillery to support an attack and deliver withering fire met with an offensive orientated tactical spirit. Indeed the French even had/have a word for this 'Elan'.
Unfortunately, technology/industry by 1914 had developed to a point where artillery was suitably powerful enough and numerous enough to be deployed on far wider scales than previous conflicts. Thus when infantry platoons began their advance in columns with the idea of achieving breakthroughs and sweeping flanking manoeuvres they hit the harsh reality that everywhere they may attack would be defended by these new guns. The so called 'war of position'.
Compounding this, battlefield communication was still highly depended on human runners or riders to carry messages between commanders and HQ which would make it very difficult for high level commanders to react to these tactical level situations to redeploy their own heavy assets or re-direct an advance. It could be said that these factors lead to the so called 'attritional warfare'.
However it was because of this situation that new military doctrines and tactics were invented in response to the 'war of position'. Suppressive fire was one of the first. Although it had been seen and used in past wars, the machinegun and bolt action rifles allowed this tactic to be deployed in regularity. Furthermore, the notion of 'shoot to kill' had yet to be developed, therefore most soldiers were unlikely to actually 'shoot to kill', but many would still keep their heads down if their position was being fired on, therefore from an infantryman’s perspective suppressive fire was an easy way to disrupt the enemy. Indeed, it may be that because may soldiers of this age were conscripts with no intent to kill the great war may have been prolonged slightly by the fact that when two groups of soldiers met on teh field they may not have pressed the battle as actively as they later did in WW2 where there were committed ideological notions to actually 'shoot to kill'.
Around the same time, two other tactics developed the notion of the 'infantry wave' and entrenchment. Again both these tactics had long been used in other wars, however in the great war for the first time millions of soldiers faced off against one another and battles no longer lasted for hours or a day, but could be a continued offensive for several weeks. The infantry wave was a concept that through shock and the repeated application of fresh unit after fresh unit being committed to a fight the enemy would finally exhaust ammunition, supplies and fighting resolve, indeed thousands of men could be committed to a fight with the commanders unable to affect a response in reasonable time due to the aforementioned communication channels available. Therefore in early modern warfare the human wave tactic exploited an opponents ability to quickly adapt to the situation on the ground.
Entrenchment started as a response to the new power of the artillery but also because it allowed commanders on the ground to thwart the human wave tactic by giving themselves an advantageous prepared position to meet the enemy advance on. Thus contributing to the trench warfare in the west.
As the war would drag on infantry would develop infiltration tactics or 'huttlier tactics' as they may have been known then to counter prepared positions and the inefficiency of the human wave. Later specialised platoon roles would be developed to allow light machingun teams to deploy suppressive fire or mortar teams to clear a dug in position position.
By the time of WW2 these concepts had developed in the schools of methodical battle that emphasised superior fire-power destruction in detail and synchronised tactical offensives. At leas that was the case for the allies.
However on the German eastern front the Great War had been much more mobile. While the allies could muster lots of guns onto a relatively narrow front where reinforcements were relatively close and various existing fortifications allowed for a war of position and entrenchment the east with it both wide and deep front and poorer infrastructure meant that a fortified position could be bypassed, or a commander that took the initiative penetrate well passed 'the front' to attack key positions.
This is later seen in German WW2 doctrine with emphasis on the bypassing of strongpoints and directive command - particularly a concept of the 'tempo of battle'. Where they must be an battle the concept of the schepunk or focal point developed to locally breach the defenders position by ensuring that overwhelming support was present for the attack.
While it is arguable that without the great war we may not have seen the development of such doctrine or tactics, it is arguable that two scenarios could have ensured that OTL Great War could have been much more mobile.
First Scenario:
A medium scale conflict circa 1896 to 1910. The machinguns and modern technology of the bolt action rifle and artillery could have been seen on the battlefield properly rather than squashing colonial natives. This would have allowed the Great Powers more time to develop new tactics and 1918 may have occurred a couple of years earlier with great movements on both sides.
Perhaps more lessons from the Russo-Japanese war?
Second Scenario:
The Great Powers have smaller armies and less emphasis to build guns or artillery pieces in the lead up to war meaning that when they did go to war there was no period of stalemate. This is quite a large butterfly.