Most prehistoric people in the hunter gatherer stage of development were nomadic with no fixed settlements. As they wandered over their territory following herds and ripening plants and "hidden" food resources in lean periods they ate whatever comes their way - roots, berries, eggs, mammals, fish, fruit, seeds. Using the Bushmen (AKA: San, Khwe, Sho, BorBasarwa of the Kalahari a an example this diet can be quite extensive.
they didnt
Yes, and they have done so since prehistoric times.
Wild berries, nuts and animals that were hunted
fish.
prehistoric sharks eat whales, other sharks and mollusks. But the megalodon eats any kind of living organism
seaweed
If you're referring to the remains of prehistoric organisms, they don't eat anything. They're dead. If you're referring to antiquated or stubbornly unchanging people, they eat whatever they feel like.
Was technology important to prehistoric people
because their teeth are stone.
Yes, its very good
To eat, to enslave, to breed from.
they did not need to adapt why would they? what would they have to adapt to? what environment change are you talking about? The people were there and that was it.