Correct. Without enchantments or traits, jewelry does nothing. Its vendor trash.
That was true in the other TES games, but since ESO jewelry doesnt have models, it doesn't even look pretty on your character.
Level determines what level of character can wear it, since you can enchant or transmute it (though I don't know why you'd want to waste transmute stones on a level 5 ring.)
Edited by VaranisArano on September 7, 2019 11:14PM
The item level will restrict the enchant you could add to it. You'll see these blanks more often at low levels. At higher levels, you'll see that jewelry almost always has a trait and will often have an enchantment on it. Set items will always have traits and enchants.