I claim that every innovation in human history has decreased the share of variable costs and increased the share of fixed costs. In support of this claim, take a random sample of technologies, e.g. the list of practical technologies on wikipedia:

Going through a List of Technologies

Prehistoric Era

• Stone tools/technology fixed cost of producing the tool, reduced variable cost of doing the thing the tool was meant for.
• Fire fixed cost of creation and keeping it alive, which increases nutritiousness of food and thus reduces the variable cost of food gathering
• Fur Clothing reduces the variable cost of firewood to keep warm
• Mining under the assumption that the resources found will be used to create tools, mining is part of the fixed cost of tool creation.
• Longboat reduces the variable cost of moving things over water
• Bone Flute (not applicable)
• Animal domestication fixed cost of domestication is justified by the reduced variable cost of other food gathering
• String after the fixed cost of making the string, something else becomes easier (not sure what it was used for)
• Painting (not applicable)
• Ceramic (art) (not applicable)
• Sewing after the fixed cost of learning this technique, the variable cost of cloth creation is lower
• Rope similar to string
• Plant domestication similar to animal domestication
• Brick after the mold is created it becomes easier to create easily stackable stones to build a house. Houses themselves provide insulation and thus reduce the variable cost of firewood etc.
• Spindle its fixed cost creation reduces the variable cost of cloth creation
• Metalworking part of the fixed cost of tool creation
• Salt cultivation the ability to enrich any food with salt would presumably reduce the variable costs of gathering salt rich foods.
• Leather presumably more durable than other clothing and thus reduced variable cloth creation costs.
• Irrigation increased yield reduces the variable cost of food creation
• Equestrianism (Hore Riding) reduces the variable cost of time to move from A to B.
• Weaving Loom reduces variable cost of cloth creation.

Note: I am ignoring military technologies, because military technology is always meant to reduce the casualties on your side wile increasing deadliness. So it could be viewed as reducing the variable human cost of lives to kill a number of enemies. Sure some of these technologies might have variable costs attached to them (like ammunition) but the cost of ammunition will be significantly lower than the human cost incurred without.

Ancient Era

• Writing Systems reduces the variable cost of keeping information alive by oral communication and memorization
• Mummification (not applicable)
• Papyrus reduces the variable cost of writing
• Ard Plough reduces variable costs in food production
• Wheel reduces the variable costs of transportation
• Galley reduces variable costs of moving things over water
• Pottery storing of food reduces the need for constant food gathering
• Metallurgy/Bronze forging better tools further decrease variable costs
• Plumbing removes the need for manually removing the waste and thus variable cost
• Abacus reduces the mental strain for calculations (variable costs)
• Iron Smelting better tools further decrease variable costs
• Arch reduce the variable cost to make a bridge, house, etc.
• Alphabet reduces the number of characters and thus the cost of learning to write
• Glass making improves insulation of houses and thus reduces the variable cost for heating
• Steel better tools further decrease variable cost
• Saddle reduces the diculty of riding for every ride
• Lock provides safety while providing a low variable cost of access when in possession of the key
• Aqueduct reduces the variable cost of transporting water
• Archimedes' screw reduces the variable cost of transporting water up
• Caliper makes measurements easier, thus faster, thus cheaper
• Crane reduces the variable cost to lift something
• Odometer reduces the variable cost of measuring distances
• Watermill reduces the variable cost of milling, grinding, etc.
• Block and Tackle (Pulley) reduces force required to lift something
• Horseshoe reduces wear (variable cost per ride)
• Paper reduces the variable cost to write something
• Aeolipile (Steam Engine) not widely adopted. But later the steam engine will allow for automation, which reduced the variable cost of many things

Honorable Mentions

Wikipedias list ends here, but to mention a couple of newer technologies

• Printing Press reduced the variable cost to copy a page
• Railway reduced the variable cost of transportation
• Telegraph reduced the variable cost of communication
• Computer reduced the variable cost of calculation
• Internet reduced the variable cost of communication again

Information technology is the epiphany of fixed costs. The amount of effort required to build a modern computer with modern software from the ground up is so insane, it could only be achieved by generations of people building on top of each others ideas and existing technology.

Future

This trend is likely to continue with ideas like self-driving cars, which reduces the number of cars required to serve the same number of people. Further out are technologies like maglev trains in vacuum tubes which would reduce friction and thus energy required to travel to almost zero - at a massive fixed cost of building such a structure. 3D Printing could result in a lot of things being merely a blueprint and material costs. But since it is very slow at the moment, its variable costs are still quite high. Which is the reason it is only adopted in areas where variable costs are even higher (like in prototyping).