This is my understanding as well. Jesus descended into the underworld, not Hell as we think of it.
I'm not sure why the Apostle's Creed says "Hell", except that it is shorter and easier to say than "underworld".
Funny that the word usage has caused so many questions and misunderstandings, though.
The use of “hell” in the Apostles Creed is an archaic use of the word that most modern prayer books now render, “He descended to the dead.” People who still use the word “hell” when reciting the Creed are either using old (or old fashioned) prayer books, or are old themselves and are still sticking to the usage they were brought up with. Nothing wrong with it in private prayer as long as they know what is being said here and not confusing it with the place of the damned, but reciting it that way in public without explanation could confuse others.