you have to make the screen shots look good as a possible, not only of what you are taking a screenshot of.
that means making sure smooth lighting is on, so you see some shadows, but also setting render distance as far as possible, or taking the screenshot in such a way that the viewer doesn't just see cut off chunks like that sea.
I think I gave some other tips on how I was wanting screenshots in the announcement post.
Thanks for trying but i won't be using those ones for the website header background, though i am needing some new ones.