I've been reading about the Navy human intelligence rating for years and I'm very impressed by how little is available on the open internet.
Navy would be my preferred branch of service, but they don't allow entry level (man/woman off the street) contracts for the school. The Marine Corps is the same way. I totally understand why that is. The Army allows or has allowed folks to directly enlist into 35M in the past, which is not a direct comparison to Navy/Marine Corps HUMINT but it will get your foot in the door. As old as I am, I'm starting to look into going active duty Army 35M, if they'll allow me.