|This giant wooden elephant is not a scientific theory,|
but it is pretty cool.
Is that a great bit of babbling? The first time I heard it, it really slowed me down. Unless a theory is disproven and replaced, it is not a "previous theory."
Some pretty sound "previous theories" like Newton's Gravity, still work pretty well, although they known not to be actually true.
Ptolemy's theory of the solar system predicts the motion of the planets pretty well, but it has the theory completely wrong.
Each new theory of science is zeroing in on the truth, and is not a random shot in the dark.
Also some theories have impressive antiquity for example, the Atomic Theory for example, has been around for a hundred years in its current form, and two millennia in general principle.
The Theory of Gravity has been around since 1666, and even though quantum gravity and General Relativity might push it aside, high school kids are still learning it.