I agree, we don't live in a vacuum of meanings. Quite the opposite, we are bombarded by all kinds of values and meanings, coming from our social environment.
The problem is that some people realise that those meanings do not satisfy them, they do not work in some circumstances, that there is something more. So the people start raising difficult questions. They search for other kind of meanings and profound values, from the inside.
The concept of freedom is one of the major philosophical questions.
However, if we look at our own personal (subjective) experience, it becomes obvious that everyone actually behaves like we do have some sort of freedom. No healthy individual thinks that they are just a dead rock in a river.
* Do you believe that you (personally) have some kind of freedom?
* If so, you would have to decide how to use that freedom. Otherwise, it's not really freedom, is it?
* Finally, in order to make any decision you have to put yourself in some coordinates, orient yourself. Otherwise, it's not a decision, but a random choice. Remember that avoiding coming up with any decision is also a decision.