We unfortunately cannot tell or state with evidence what a prehistoric man aka cavemen looked or behaved like. It is only with small artifacts,cave paintings and the sheer imaginative predictability of a human mind that we can tell how they might have acted in different situations.
Due to no recorded data(except a few artifacts found scattered and cave paintings) one can only use his imagination to think how a man who is so new to everything might act, for even a touch of wind gust is new to him .we can imagine that being a human the cavemen also had curiosity, we cannot deny that they would have even tried to lick or bite a rock if they got their hands on one while trying to quench the strange feeling they had in their stomach now modernly named as hunger, because its only human to experiment with our senses when we find something completely alien to us.
A land so foreign and frightening to them, that the cavemen tried to find a safe haven within which they could dwell for a time period without having a heart attack, which i might add also would have been new to them .the only place they felt save was when they wandered upon a small opening in the mountains, off course it was after sometime that they entered it because a gaping black hole in an unknown place is not considered safe even now in the modern times, again one can only use his or her imagination on what might have happened and caused the caveman to enter it, an animal or even a thunder perhaps.
After sometime of cowering in the corner of the cave they probably had gotten hungry and thirsty. The cavemen as you can imagine were also new to this alien feeling, so again being the most intelligent being; they experimented. We cannot say that they got right to the answer , perhaps a few even died in this race of survival .The fact that we now roam this planet as if we own it is the proof that at least one of them found out how and what to eat and drink.
The fire was discovered much later so whatever they found to eat was devoured in raw from, the water was gulped down even if it was half mud because they were fighting for survival, civilized or hygiene rules were not their first priority.
Up until sometimes ago the cavemen were portrayed as big hairy men,holding a club of bone,who were very aggressive and merely pointed and grunted when they weren't swinging their clubs at others. This was until some caves with paintings were discovered(Altamira cave in Spain), this challenged the point of view of the people who thought cavemen when were just animals with low intellect(the previously stated definition of cavemen is now used for trolls ).
The oldest known cave was Chauvet discovered in 1994 in the south of France, the paintings on the wall are said to be some 32000 years old.
The contents actual purpose is perplexing,due to no recoded history except a little evidence that they hunted and off course the paintings on the wall, the actual events of the stone age remain somewhat of an enigma.
Before Chauvet , another cave was discovered in France by a teenager boy in 1940, these caves contain paintings of bulls .The paintings in this cave are known to be 17300 years old .The first cave ever to be discovered was in 1880, hence changing the point of view of the people around the world about the troglodyte, was called Altamira which was discovered in Spain, the paintings in Altamira cave are of bison, these paintings are known to be 18500 years old.
The purpose I might add again is unknown, this could have been due to an act of decoration although no remains and evidence is unearthed to imply their long stay in those caves, that's why it is said that the caves were never troglodyte's permanent residence, they were continuously on the move, the reason of which is unknown. The paintings also could have been for communication as there was no specific language yet for they could only produce Tarzan like voices,obviously the Tarzan like voices are undecipherable as no one even now knows what Tarzan is actually trying to say when he makes that long yell of a sound when he swings from the vines. So its possibility that the paintings were a mode of communication .Some even suggest they were religious and for ritualistic purposes.
I again however might add this assumption is yet again completely lacking in any evidence. Archeologist are however working day and night to interpret the purpose of them and their meaning all around the world.