First off, if you are the Germans and hold lots of the green part of the map and the bunkers, it's impossible to attack the beach from the ships.
Secondly.
why can't the ships look right? on the map, the Thomas Jefferson looks like a battleship with huge guns, when it was in fact a troop carrier and only
492 feet long with 4 x 3" guns
The USS Texas on the map looks like a landing craft, but was in fact a New York-class battleship 573 feet long and had 10 x 14" guns
on D Day she:
The initial bombardment commenced at 05:50, against the site of six 15 cm (5.9 in) guns, atop Pointe du Hoc
the U.S.S. Arkansas again looks like a landing craft on the map, but was a Wyoming-class battleship 562 feet long armed with 12 x 12" guns
on d day she:
entered the Baie de la Seine on 6 June, and took up a position 4,000 yd (3,600 m) off "Omaha" beach. At 0552, Arkansas' guns opened fire. During the day, the venerable battleship underwent shore battery fire and air attacks.
Thirdly
Why the hell can't the battleships bombard the German positions?
Every time I play this map you can only win by taking up the shore defence positions.
That's not how D Day played out!