The levelshot really is not great yet.

I would suggest to first create an Art-concept before
beginning to stuff the levels with objects already.

Try to find a certain style of colors, look and Architecture.
And try to make it simple enough, that you know you can
create enough content following this artstyle - to actually fill up a whole game.

One such an approach would be:

"We want brounish-grey architecture, with expressive thick elements, and a low polygoncount.
The highlights are green and blue elements for Lights and
Underwater windows. White and red light-ambience for points of interest."