getting there is more than than having got there. or more down to earth fucking is much better then having fucked.
having your character start out as an already accomplished pirate counters against your intention of providing a back story, as the first question the reader asks himself is, how did he become a pirate captain?
also little is provided about his intentions and desires. we know about his past but we dont know about him. If you want to leave it wrapped in a mysterious aura then you should work on encouraging the readers curiosity about the character providing them with more questions to ask about his past, you can only do this by providing more input but without providing solutions/answers. eg "he was the only survivor of the battle of gilgamesh VII" begs you to ask, well how did he survive.
hope this was helpful, narration is a continuous work in progress, keep at it
