Super easy, barely an inconvenience

Wait, what do you mean with no point of reference? If you were physically there the whole world would be your point of reference. You could point at a rock and make a grunting sound and somebody would eventually tell you the word for “rock”. They’d have actual teachers. How you would go about accessing them is anybody’s guess, but hey, they’d exist.

The hard part would be learning it when there’s nobody left to speak it because making grunting sounds in the general direction of rocks is famously ineffective at decoding ancient documents.

This exact thing has happened many many times in history. Not someone transported through time, but someone travelling to a place where nobody (or virtually nobody) speaks the same language, or even one related to yours.

I mean, for the extremely obvious examples, before the Columbian exchange, nobody in the Old World (Eurasia/Africa) had ever encountered any New World (Americas) language and vice versa. They managed to learn how to communicate within a fairly short time period.

But this was just the most obvious example. Until relatively recently (like past half millennia, or so), it was common enough.

You’d learn through immersion. You hear the language every day all day. You try to communicate by pointing and gesturing. Pretty soon you start picking up individual words (point at a piece of bread and say ‘bread’ over and over. Someone is going to respond with their word for bread. Do that a few times and you’ll learn the word for bread, etc, etc). That builds into common phrases. Before too long, you’re able to hold very rudimentary conversations, and it just builds from there.

If you live in somewhere where said language is spoken by everyone around you, you’ll start to understand the language over time no matter what language it is.

You will always have points of reference. Common things that you see and do throughout your everyday life. And you will hear people speak of those things in the native language. Eventually, you’ll start to catch on and learn the language.

How difficult would it be? That really depends on the individual and their ability to pick up languages.

Language is natural to humans. It would be hard, but you’ll eventually get there if there’s no alternative. Think that babies learn how to speak without having any previous language of reference. It’s just a thing our brain does spontaneously. Watch or read Shogun, you’ll notice how multilingualism is actually more common than we think. And historically people have always spoken several languages. Depending on which point in time you’d get to ancient Egypt (we are talking about a really long period of time, over 3 thousand years), the high class would probably also speak Greek, Latin, or Arabic. Depending on diplomatic relations and pressures. Not to mention the lay people would also probably speak other languages alongside Egyptian, like Domari and Hebrew.

Another interesting thought, if you traveled to late ancient Egypt, learned to speak there, let’s say five years or so. Then traveled further back in time to early ancient Egypt, you probably won’t understand a single word again. If you traveled to the 800s England, you wouldn’t understand the English they would speak.

points at date

Egyptian mf: " 𓂧𓄿𓏏𓅂"

Repeat

The key to all this is UNLIMITED RICE PUDDING!

Depends on the person. I can tell you it is very likely I would not be doing very well after years but I know some folks who would be able to do as well in weeks or months.

One technique I’ve heard being used by Bible translators to learn new languages: show some curious/interesting object, you’ll learn the phrase “what is this?”, then start pointing at everything and repeating it.

Ancient Duolingo, duh…