Well, even though I have the original books, I play my current game using the "Star Wars: Classic Adventured" retroclone.
Ah, it makes sense now why you had so much trouble learning the 1E initiative system. Classic Adventures doesn't use the original damage chart. It uses the one from the upgrade (or, is it from 2E, I forget).
The problem is how Stun in handled. In 1E, any hit will stun the target. There is always a result from a blaster hit.
Under the damage system with the Classic Adventures book, a character can shrug off a Stun with a high STR roll.
This is one of those "unintended consequences" things. You change one thing about a good set of rules, and it makes another part of the game not work well. With that type of damage system, the 1E initiative system suffers.
1E
What happens is that hit will happen early in the combat round, and the minimum that will happen is that the target hit will go down and be stunned, losing all his actions for this round (and starting next round on the ground).
This will weed out characters and their actions, and what seemed like a complicated combat round becomes very simple as targets are hit and lose their actions.
For example, you've got three Rebels: R1, R2, and R3. And, they fire at four stormtroopers: S1, S2, S3, and S4.
R1 fires twice at S2.
R2 fires twice a S3.
R3 fires once at S4.
S1 fires at R2.
S2 fires at R2.
S3 fires at R1.
S4 fires at R3.
Now,that looks complicated, right? But check out how simple it can play out using 1E core rules with the 1E core damage system...
First, we break the combat down into clusters of who's fighting who.
A Combat Cluster.R1 fires twice at S2. S2 fires at R2. R2 fires twice at S3. S3 fires at R1. S1 fires at R2.
These five characters all roll their first attacks. Then, we simply resolve the attacks by highest attack throw first. Here's the order: R1, R2, S3, S2, S1.
R1's roll is successful, he hits S2.
So S2 doesn't get to act this round--he's been shot.R2's roll is successful, he his S3.
So S2 doesn't get to act this round--he's been shot, too.S1's roll is successful, he hits R2.
So R2 goes down, with a minimum of a stun, and he loses his second action this round.Who is left standing for next round? R1 and S1.
Combat Cluster 2R3 fires at S4. S4 fires at R3.
Both roll their attacks. The higher is R3. He hits. S4 is down and gets no actions.
Who is left standing from this cluster? R3.
So, we start combat round two with R1, R3, and S1. R2 and the other troopers will start at a disadvantage of getting off the ground from a stun or may have wounds (or may not be able to act at all).
The point: Do you see how having the stun be the minimum result thins the actions of a complicated combat round very quickly and makes the 1E initiative system fast and fun?
If we allow a character to shrug off his stun, then the combat round starts complicated and stays complicated, and the 1E initiative system doesn't work as well.
My guess is that this is why the game designers went to a traditional initiative system in 2E, because they changed the damage system. 1E's beautiful initiative system didn't work like it did in the core rulebook.
