Well, of course you need more than small amounts of protein.
Vegetables are what humans are supposed to eat. We need these for the nutrients and fiber and antiinflammatory effects. Small amounts of protein from fish, poultry, meat and/or nuts is helpful. Many people do not handle grains well, and dairy tends to cause inflammation, so it is not as important as vegetables either. Fruit is fine.
Can you say more? Why would you want to eat no vegetables? The only people who live without vegetables, if that's what you're saying, are people who can't get them, such as Inuits and Plains Indians (historically) and some Tibetans for much of the year. Now that we can get vegetables year round why would you want to not eat them?