While that particular page may be simple stuff for a big price, going to the site's front page shows some really beautiful creations that are being sold for what is basically 2 to 0.1 hours worth of pay, and probably took many, many hours to make.
And, even if you do not have ownership of the blocks, the creativity and design that goes into the particular arrangement of the blocks is something else; that is exactly what copyrights are intended to protect.
No one owns words.
An author owns a particular arrangement of words.
No one owns colors
An artist owns a particular arrangement of colors.
No one owns blocks.
A minecraft artist owns a particular arrangement of blocks.
And yes, "owns" is the wrong word in each of those, but I don't know what word properly represents the concept of having a creative claim sufficient for copyright.