Basically the title, you need to use the skills you have now and be a productive member of society.
I don’t mean go back and show the wheel or try invent germ theory etc.
For example I’m a mechanic i think I could go back to the late 1800s and still fix and repair engines and steam engines.
Maybe even take that knowledge further back and work on the first industrial machines in the late 1700s but that’s about it.
It is easier to spear fish underwater. You do not have the refractive index of light to deal with.
That is with modern equipment though
You did not understand the abstraction. I covered all of human history from hunter gatherer to modern.
Are there hunter gatherer methods of launching a spear effectively while underwater? Plus wouldn’t it be much harder to see the fish.
Scuba or snorkeling – diving leads to spear fishing.
It helps to have modern elastics to make a riffle like spear gun. When under water, big fish are easy game. You’ll see them easily in the ocean and reasonably well in large rivers and lakes too. With rivers and lakes you can just noodle with large catfish. If you reach into holes and cervices, catfish will bite your hand. It is more like sucking. You just pull them up, no tackle or equipment needed.
Without modern elastics, any bow or torsion based energy storage system would work to make a crossbow like action. I could easily flake a rock to make a crude knife, and fashion something out of some sticks.
I would probably struggle most with my chemistry using organics I find in nature. I know stuff like the best bows are recurved with composite wood. Ultimately, I am loosely aware of the innovations of Watts with the pressure regulation of a steam engine. I know how to make bloom iron. And I know the basics of indirect heating and atmospheric control of the Bessemer process. Additionally, I am aware that the key to lathe precision is a heavy base, and that a lathe screw lead is able to cut a more accurate lathe screw lead, and eventually achieve any machine precision desired. Prussian blue or any dye based pigment, is used with a special thick chisel to hand scrape metal flat. Magnetite is the primary ore for iron. Steel is all about precision control over the carbon content. Heating calcium carbonate is super handy. Boxite requires chemistry to get to the aluminum. High voltage arcs across electrodes in air will make nitric acid, but guano is the most accessible form of nitrates at smaller scales. Potatoes are the most important food source to scavenge.
A general deep curiosity and willingness to explore are the key personality traits. I love learning at a fundamental level where I actually understand stuff. I am not all that bright, just a jack of all trades type person where I have a very broad set of skills and understanding of the world. I’m a swiss army knife – all the tools, but the world’s shittiest scissors.