I have no agenda when it comes to Dak so I am posting this simply to be informative.
I am also not sold on Lance and so far, I have not seen anything from him that gives me optimism that he's a future franchise quarterback.
That said, I am not pessimistic about him either. I think he just hasn't had time to show if he can be that guy.
The Cowboys traded for Lance for two reasons. One, to provide a fallback option should they lose Dak for the year to injury and two, to provide leverage and a backup plan for the team should Dak hold out or the Cowboys move on from him at some point.
A third reason is this also gave the Cowboys a top draft pick quarterback they could coach and trade later if necessary.
Now, on to the biggest point.
Those guys you listed have a LOT more game starts under their belt, so of course they are worth less trade-wise.
Those other players were replaced because they were given the starter job and after MANY games they proved they could not do it, at least for their respective teams.
Lance on the other hand, was given the starter job, then soon after was lost for the season.
His replacement came in and played very well, and that is why the 49ers moved on from him rather than because he couldn't do the job.
The 49ers smartly figured they could get more for him immediately rather than waiting it out another season.
I don't know if Lance is going to ever become a franchise quarterback and I don't know if Dak is going to be here in 2025 or for the next several years.
What I do know is that unlike 99% of the moves the Cowboys have made with regards to quarterbacks since drafting Aikman, trading a 4th for Lance last season was one of their better moves in my opinion regardless of how it works out.