No, the spiels were not always there. They were added in roughly 2002/03, during a Disney Parks worldwide safety initiative, following a pretty devastating incident at Splash Mountain (in addition to a few others), which led to two specific additions to just about every ride on property:
- All of the white safety placards you see on nearly every ride vehicle now (many joke they look like "hold hands/no disco dancing").
- Safety spiels being added at every attraction in English and Spanish.
Prior to the pre-recorded safety announcements, the bellhops gave a much longer "live" safety spiel, asking guests to remain seated, hold onto loose articles, etc. It was not long into the "seatbelts" version of the ride that the automated recordings made their debut.
Personally, I think the pre-recorded safety spiel was a huge downgrade to the theming there. The bellhops live safety spiel really could be quite memorable for guests, especially if you got a great bellhop. A little "show before the show." Once added, the pre-recorded announcement made it seem like any other ride.