I notice that a lot of war movies and games portray storming the beaches of Normandy as a very grueling and violent undertaking for the allies - but then I have to ask, could the pillboxes at the top of the beach have been destroyed by the battleship guns if pointed the right way?
Why didn't the allies completely pulverize the beaches as to ensure all German reinforced defensive positions were destroyed - seeing as the allies knew exactly where they were going to land and probably had done reconnaissance and likely saw the pillboxes and barbed wire etc?
Don't take Saving Private Ryan and its imitators as representative. Yes, Omaha Beach was a grim and hideous slog for the American landing force there - but it is not the totality of the five landing beaches, and the other four were much different.
This being one of our very common questions, I shall direct you to my D-Day Compilation, which addresses most of the questions you have. Should you have further questions, please don't hesitate to ask them; it's entirely possible even I can provide some more answers, as I've done some reading into this topic as well.