You could fold all the other service’s missions into the US Navy.
And all the compromising they’ve done since Tailhook.
No, the navy does not “have its own land force, the Marines”. The Marines are separate and answer only to marine officers up to the joint Chiefs of staff. The commandant answers to the civilian Secretary of the Navy.
Marine units are not under the command of navy officers, except for joint commands.
By that standard, Navy forces are sometimes under the command of USAF or USA officers.
The Navy is the most prominent branch of the military in America because America has been, and always will be, a naval power. I believe that over time the Navy will be the one spearheading our quest for space, not the useless dandies it in the Air Force.