trebuchets now exist in 3500 BC

We learn how to generate electricity in Secondary School, it's pretty simple and fundamental to understanding electromagnetism, and it underpins our whole civilisation's existence. Surely you'd remember that?

In the vast and intricate web of human understanding, where knowledge weaves its delicate dance with experience, I find myself positioned, albeit humbly, at a nexus of comprehension. This vantage point, carved out through relentless introspection and a profound engagement with the world, allows me to unravel, elucidate, and perhaps even, in some modest measure, illuminate the topic at hand with a level of profundity that few might grasp.

Turning our gaze to the curious and somewhat perplexing phenomena of temporal voyages, or what is colloquially understood as 'time travel', we encounter a host of philosophical and practical quandaries. Within this entangled morass, there arises a lamentable observation: the entities, or perhaps the emissaries, dispatched from the annals of future chronology to our present juncture, don’t always seem to represent the pinnacle of their epoch’s capabilities. The Jungian shadows of the future, one might muse, often obscure the brightest luminaries, leading to a situation where we are not always graced with the presence of the 'best' or most optimal representatives of these temporal sojourners. In simpler terms, they aren’t always sending their paragons back in time, but rather, we find ourselves navigating the intricate dance with a mosaic of characters, each embodying a unique facet of their origin's potentialities.

No problem, just tell them to ask from Baghdad, they should know where it is. :) A jug of wine or vinegar, one electrode of iron, another made of copper, voila... the Baghdad battery.

If this concept intrigues you, I recommend watching Dr. Stone.

Not my idea, but sometimes it's just enough to listen to "crazy" people. They might not know what to do with wire seemingly spinning itself, but you will have much better idea what can be created with it. RIP Terry Pratchett

They would probably kill you thinking you're into witchcraft or something.

But first, you need all the guns (and other modern weaponry) to gun down anyone trying to kill you. Might be useful to make them listen to you as well.

I take these two completely different looking rocks, dig a small hole between them, and pee in the gap.

Electrolytes! It's what every caveman craves!