In the film, Bourne starts lostin the middle of the sea, without an identity. A few fishermen rescue him, and he discovers he has a lot of skills, but, eventhough most of them are really valuable, the most important thing he wants to find out is unknown to him. What's his name? Who is he, apart from an amount of incredible habilities?
After some research, he finds some passports with his photograph. Loads of names, loads of identities. So, he still has the same problem, who is he?
That makes me think. We live linked to our names, and any part of us, any friend, any skill, any scar or any memory acts like chains that bind us to our identities.
Why is it as important to us to know who we are? Why, if most of the time we don't really know, but we pretend to?
We are who our enviroment wants us to be, we are how we get adapted to it.
So, in the end, we end up being who we pretend to be, although, sometimes, this means losing our real and original identity.