How far in time? People, if you are unfortunate enough in life forced to travel back in time more than 600 years, at very least beg for total disease immunity and auto language translator ability. Our current language only useful within 1 - 500 years from your current time. My rec - sousei no taiga.
Spoiler: this is a huge walltext, at first i just wanted to point out how is really silly the commentary in the video and and how it's right that it is used as comedy and not realistic but i got lost in the process and did not even focused on the thread itself and when i came to me it was already huge walltext so i stopped myself and also i'm too lazy to delete all my effort in writing it so i put this spoiler tag as warning so everyone read at your own risk this a walltext. . this is not totally true and is a huge misinterpretation of the topic of "going back in time and enlighten the civilization" but where i do agree that 99,99999999% of people do not have a clue about all the core technology of our common living world works and thus would not be able to explain it correctly, there is still one main point and perhaps the most important point of it all! to reach the point where we are and in the long run of human life, the humans took multiple detours before reaching the finishing line and all those detours not only consumed money but also years and years of multiples great minds, some failed because their methodology was proved false or flawed once the final result came out, so yeah you may not know how microwave works, or how a fridge works and be on the 99,9999999% of the world that really have 0 clues about all of this, it does not matter, just by going back and telling the greater minds of that time about everything you know about, even the most futile knowledge you learned in high school step by step,the result of all of this is already enough to skip years and decades of development, maybe even centuries with simple descriptions about all the products of daily life , because they would already know the "end game" and thus there is no need try everything, only fill the missing pieces of the puzzle even if those columns are huge for any of them at first glance and sometimes they may even surprise us by creating something entirely new since it is still a lot easier than starting from 0 and of course you can not also start and ask to build a computer when you are living in the fucking middle ages, or earlier, you need to play it step by step. let's be realistic a little: if we are going back 500 years ago? to the time of Renaissance , when people still uses horses and animals, there is a lot of futile knowledge that there is no need to be a expert that would already change the entire industrialization of human race by years and decades and maybe even centuries like : steam power, there is no need even to explain how a steam motor works, only tell them that is "possible" and make them focus on it is enough for someone on that "consul" to figure it out, after all you may think you don't know shit about steam motors and all the rest, but in reality try to think it thought right now when reading this and i bet you should be able to imagine a rudimentary steam motors that transform the power of steam in another form of power and this alone is enough; of course your rudimentary "motor" may not generate enough power to do jack shit in that world but is no problem; the prototype alone is enough to give them the entire road to pursue from: from discovering that the power is generate from pressure; and to have enough pressure you need higher sealing of the chamber; and to have higher sealing you need to work around new techniques of metalworking and this goes on. fossil fuel and combustion power, the same as above; there is no need to figure it out as well, just shows the possibility and someone in the big world will discover too. world map made by a awful hand drawing from you, since at that period the "old world" was starting to explore the seas and discover other continents like Americas etc; self explanatory with a MAP it does not matter how bad the drawing is, as long they know more or less where each "place" is, they could go there, it could be hard to find a specify island in the middle of the ocean, but continents and everything else should be easier and holy shit, with map like that they could more or less start to figure and plan out sea routes and cut short decades of studying and planning, this could be capable to save maybe decades worth of "time", for the world as "whole" in this period. Alloy works, iron was know by the world far long ago and in a sense alloy too but there was not really a in deep use of it, mainly because it was difficulty to produce but now with fossil fuel and other amendments it would push the development of new and powerful furnaces capable of producing large batches of alloys far earlier than our current world where everything only started in the earlier 1700-1800 but in this reality you could push this to the renaissance period of earlier 1500. so yeah, everything that i talked about seems a little silly and you don't really need to know how everything works or you may not even "live" to see the end of it but only by showing them and make them believe is enough, as long you direct them to the "RIGHT PATH" is enough to cut centuries of development, don't underestimate the wisdom of human race, in the past things like iron-fossil fuel in their respective "ages" was laying around in nature because no one really knew what to do with them and only once people "discovered" it's uses that everything changed and this exactly what you are doing, you are telling people the value of those things decades and centuries before someone even start to "think" about it and thus this alone can change the world so again by the end of it the MAIN real problem that the person who goes back in time would have is not about the technologies break thought or if they could really "BUILD" something but to convince everyone around them they are not some crazy man possessed by the devil, so everyone can really listen and put not only money but also their times to work around the ideas that you told them , after all we all know that the "past" was not really flower field where everyone is happy go luck man living in prosperity.
Maybe try I Have a Mansion in the Post-apocalyptic World The MC moves back and forth between 2 time points often, brining tech and weapons.