A time-travel experiment sends a volunteer back to the stone age.
The Stone Age begins with the first production of stone implements and ends with the first use of bronze. Since the chronological limits of the Stone Age are based on technological development rather than actual date ranges, its length varies in different areas of the world. https://www.ancient.eu/Stone_Age/
The modern person would find themselves in immediate danger from disease, injury, animals and indeed other humans. Unless they were a hardened survivalist they might even die within the first day.
Unfortunately something goes wrong and the traveller is stranded for ever.
What should a modern person take with them to stone-age Europe in what is now Neander Valley in the German Rhineland, to survive as long as possible or preferably indefinitely?
They can only take one set of warm clothing and a backpack containing 80 pounds (36.3 kilograms) of whatever supplies will help them best. When these supplies run out they cannot be replaced.