The skull looks like it's peeking playfully into the front image area (when you look at only the front cover) which might not be the idea you're going for. For that reason I'd suggest moving more of the Jolly Roger into the front image area.
The title, subtitle, and author text sizes look turned around to me. You are a new author so you will not sell the book on the strength of your name yet. I would suggest making the title the largest typeface, your name the second-largest, and the 'Episode One' (if you keep that) would be the smallest of the three as I think it is much less important for the reader to notice right away. So something like this:
Vengeance:
A Pirate's Tale
Episode One
Filepe Fernandez
You might get away without the colon if you bold the main title or switch it to all caps as so:
VENGEANCE
A Pirate's Tale
Episode One
Filepe Fernandez
I like the colors you used overall.
On the back flap I don't mind the circle for your photo, it seems to follow the pirate theme (as though you're looking through a telescope) though the rectangle with the beveled edges would be a lot better if you could find more of a ragged map-type image for it.
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