I agree - Ruby Princess was launched on 2008. 14 years out of a typical cruise ship life of 40 year is really not old. But the OP specifically mentioned Ruby, so here we are.
If the Carnival ship was Fantasy Class, I feel your pain. But we've sailed on the Grand Princess (built in 1998) and it was fine. Lots of balcony rooms and mini-suites. Three main dining rooms, two good specialty restaurants, scads of bars plus Alfredo's Pizza, which very few Princess ships have.