I absolutely agree (I didn't say it wouldn't change things), but the first decades/generation would still be pretty basic, much of the knowledge wouldn't be applicable until you build your tools, get basics sorted, build safety nets, etc.

For everything you need a willing society bcs one individual can't do it all - it's either you dig/build one well & others feed you or you do the efforts communally. Same with metalwork, that's a whole specialisation in the most basic sense (you need a workforce & resources for them to gather ore, work it, and forge anything of useful size - metalwork to produce a few grammes of metal per year isn't worth it, so you need a city-sized community at your disposal, and you need to get to that point ... unless maybe as an expensive way to just pass the knowledge for later gens to put it to good use, which might be successful, unless forgotten or the community doesn't survive).

Animal domestication can take generations too in some cases (bovids), you need to first focus on docile females, and once they stay in a designated area (either like a valley or even fenced fields), you need the resources (food) to keep them alive there. So you need to build up agriculture at scale first. That why we found the first real domestication evidence around ancient cities, not random villages.

12k years ago is the stone age and before agriculture. The ice age would just be ending. You don't have the calories to do much beyond exist.

If the average person went back 10k years they would be regarded as insane or heretical. Even assuming communication wasn't an issue, way too much of your knowledge is built upon things you don't understand and don't exist. You can't do anything with electricity until you can refine metals and make copper wire. No average person knows the precursor plants for medicine. Brick making is beyond the average person and you wouldn't have a kiln anyway. Working without metal tools makes most processes the average person would know impossible.

I absolutely agree (I didn't say it wouldn't change things), but the first decades/generation would still be pretty basic, much of the knowledge wouldn't be applicable until you build your tools, get basics sorted, build safety nets, etc.

I'm trying to make the distinction between the ability to just 'make' as a proof of concept & actually apply that knowledge at scale that makes any difference in that accident context. Like metalwork - without (smol-)city-sized communities (labour, and accumulated resources like winter food & shelters) it doesn't make sense bcs you don't end up with enough use-cases.

(Ofc immediate location is a great factor in what knowledge is more applicable and what not - surviving in the Arctic circle would be much different to the some savannah).

animal husbandry could get you way more food per animal in a generation

My dissertation chairman was involved in a research project in India back in the 1960s. Some agricultural extension folks had gone there because they had assessed Indian cattle as "weak" and "sickly" and were trying to introduce American breeds as a substitute. The locals wanted no part of these animals and eventually the researchers tried the radical approach of asking them why not. Turns out that while these cattle could plow 50% more land in a day, they ate twice as much food as the Indian breeds.

The light went on in their heads and they set about attempting to cross American cattle with Indian cattle and breeding the most efficient animals. Turns out they couldn't get any more efficient than the original Indian breeds.

How do you get iron ore in quantities that would allow to build anything worth building & maintaining?
(And what would you possibly use a resource-extremely-hungry steam engine for that needs to be fed that a wooden watermill couldn't do? You would need to build up society/economy even to justify a usecase for a watermill, otherwise you just build a monument.)

You could build an electric battery 10k years ago, but what for?

Where do you get species directly suitable for animal husbandry?

Or ppl to produce & use higiene products?

I can go on but in short there's loads of knowledge pretty much anyone can bring to 10k years ago that changes lives significantly.

I absolutely agree with that.

I'm a bit skeptical about the stream engine just because it requires not just metal working but precision metal working where a piston needs to form a seal with the tube it's in not just at one place but anywhere it moves in that tube, to spin a shaft without wobbling to the point that it comes apart at the intended speed. Even more difficult if it needs to be hardened, since a bit of warping is common during a quench.

I think it's easy to take a lot of things for granted and miss that modern (or even just industrial age) things aren't just the result of advancing a single tech tree but multiple tech trees coming together at the same time. Like I didn't even go into the lubricants and gaskets a motor requires.