i believe toothache would be the least of your problems, chronic exposure to white phosphorous will give you fossy jaw which… just straight up kills the jaw and makes it fall off, at least they don’t have to go out of their way to remove it! yay…

afaik travel wasn’t even particularly rare, it was just rare that you’d travel very far. Certainly in england it was expected that you’d travel to london or whatever for legal reasons at least like once or twice in your life, and of course merchants existed.

but also a really significant travel no one tends to mention is going on a pilgrimage to jerusalem! to my knowledge most people managed to do it once, and that’s a massive journey to undertake without modern vehicles!
thankfully since religion was so important back then, pilgrims were afforded quite significant privileges like guaranteed free food and housing and iirc travel from anyone, to the point that pretending to be a pilgrim was quite a severe crime.

you can use wood ash, it won’t be a very wholesome or good soap but it gets the job done and is easy to make. Though of course if it’s easy to make then why would people buy much of it from you?

I think it wouldn’t be too hard to convince people to use it for cleaning off obvious messes, way harder to convince them that “oh you see actually diseases are caused by these tiny creatures you can’t see, but trust me they’re there and my product will get rid of them!”.

afaik one person is far from enough to set of an entire pandemic, especially with a much lower population density and no rapid transport.

it’s feasible that they doom a village and get hunted down, though.

the real trick is to find some appliation for the technology that is easy enough to build that you don’t need later advancements to pull it off, yet useful enough that anyone is actually going to bother doing it.

or like, be really good at marketing

to be fair i think the fact that it started in the US is quite vital to it taking off, if you tried it in mainland europe the local priest would come over like a mafioso and politely explain that if you were to have an unfortunate accident then your soul would be spending eternity in hell.

ah yes the famous hunter-gatherers of the 14th century…

considering the modern population distribution, the vast majority of people would end up in places that were large urban areas even back then.

honestly this might actually be the best idea, for most of human history people have been absolutely bored out of their minds and sharing news/stories/songs and really any sort of entertainment has been a perfectly legitimate way to get free food and housing.

any of us could almost certainly just live as travelling bards and do side jobs for actual monetary pay, provided you can get over the embarrassment of performing for an audience, and of course learn the local languages and translate the stories you remember.

keep in mind that historically all the successful scientist have been really quite rich, so make sure to find a noble you can impress and get to sponsor you at first

you might well also die from being called to arms to fight for your king… sadly we won’t be rid of tyrants until we collectively oust them and ensure they are never allowed to rise to power again.

for reference they would almost certainly not murder you for not being christian, at worst you’d be forced to convert and only if you refuse to do that would they sentence you, and even then they might well cut a hand or ear off instead of outright killing you.

you can make impromptu harsh soap by just washing your hands with some wood ash, your hands will probably be chronically dry and red but at least you can definitely have reliably clean hands and tools, combined with wearing some thin leather gloves whenever you’re outside the home.

i mean i don’t think it would even be that difficult to just always carry a bar of soap with you and make sure to boil your water and only eat well-cooked food, and wear gloves as often as possible.

sure people would think you’re silly and annoying but that’s a pretty cheap price to pay for not catching terrible diseases.

OP tried to clarify but seems didn’t clarify enough: that’s talking about normal frogs with normal eyes, they use the back side of the eyes to push down food, presumably it doesn’t feel any worse for them than you poking the side of your eye through the eyelid.