Yes, the "young earth creationists" are those who believe in literal 24 hour days. "Old earth creationists" believe it may have taken millions or billions of years, but still all things were created by God. Even the "old earth" creationists usually believe that the story of Adam and Eve, and Noah's flood are literal, contrary to scientific evidence, and generally deny that species evolve.
I'm more inclined to believe that the creation story found in Genesis is a modification of an earlier Sumerian (or related) creation story, altered to be compatible with monotheism as taught by Moses. The modification to the older story would have been made because the Hebrews would already be familiar with it (since historical evidence shows that their religion was actually part of the wider spectrum of religious beliefs found in the area), and having a new, monotheistic, creation story would help them to move forward out of polytheism and henotheism (that is the belief that there are many gods but the worship of only one).