Much of what a human learns is lost to the cosmos but there are instances in the scheme of things when an idea blossoms and life is changed for the next person in line. The proverbial wheel, the recently obsolete movable type, the boom and bane of the industrial contraptions, the hyper active electromotive force and fortune of the world, and the most effective mouse trap of all times the integrated circuit.
Each of the future changing ideas are the children of subservient thoughts and preliminary concepts. Are they, were they inevitable or would the world be a different place if the person thinking the thought either did think it or was not in the right place at the right time. There is quite a bit of anecdotal evidence that throughout history there was more than one person who has the same or similar idea at nearly the same time. So the air plane, the car, the television and countless other things were inevitable.
Does that make people expendable? Can whole villages of people be brutally massacred by the Gigues Kahn's of the world and it not make a bit of difference to the remaining world's population. Would we still arrive at this future after several millennia? Does it mater to the future if half of the world's population falls ill and dies from the bubonic plague? The is some evidence that over population was a contributing factor and the plague only hastened the eventual death by starvation. But was there an idea whose time had come and the person who was going to bring it to light unexpectedly die. Sentencing the world's population to time at hard labor instead of revolutionizing the world and saving all of those people. Only to cause the world to arrive at over population in the 19 century rather than the 21st.