Here is an interesting sidelight which illustrates the difficulties of interpreting experience when there is rapid technical change as well as the problem of hindsight.
The British General, Sir Ian Hamilton, who led the Mediterranean Expeditionary Force in the Gallipoli Campaign, was an observer of the Russo Japanese War 1904-5. There he witnessed Japanese Infantry charging entrenched troops with success 'the successful Japanese infantry assaults convinced him that superior morale would allow an attacker to overcome prepared defensive positions' He was observing at the Battle of Shaho, see https://en.wikipedia.org/wiki/Ian_Hamilton_(British_Army_officer). This enthusiastic reaction is also quoted, in a critical way, by Paddy Griffith in Forward Into Battle, Random House, 2008, ISBN 978-0891414711 - which is about the evolution of tactics. However things are seldom as simple as they seem. Hamilton was not one of the western front generals and was well aware of the role of specific circumstances. In an earlier battle he saw poor Russian fire tactics (volleys which he compared unfavourably to the Boers marksmanship) stop a Japanese Advance. See Rawlinson: A Staff Officers Scrap-book During the Russo-Japanese War Vol 1, all of which is at https://archive.org/details/astaffofficerss00hamigoog/page/n144.
To come back to the point (coping with unprecedented change) Hamilton was born in 1853. Along with the other first world war generals he was living through increasingly fast change over a short time. The continental armies had scale and conscription right from the start. The British had additional challenges, their army was a quarter of the size (France Standing Army and Reserves 5 million, GB 975,000, The BEF only 200k). The army including empire expanded to over 8 million it was like nothing Britain had ever had before. With such an expansion, because of it sheer size and aggregate level of training past experience was massively diluted and became difficult, if not impossible to apply. After the initial shocks adaption took place, one adoption was to rationalise the killing as attrition. All the Generals were products of their time, the had been told to win and expected people to be killed, they didn't have our hindsight.
If we have to learn the hard way on climate change, as the military and political establishments did with the technology of Interstate Industrial Warfare, then there may indeed be grounds for pessimism.
Part 2 - Assess - Timeline - Past - History Overview - The Recent Past