>>544125819
Yamcha, Tenshinhan and Chaozu benefited more from Kami than Goku's weak ass did. The reason Goku was always one step ahead of them was that he always got training from the new master before them.
>Krillin and Yamcha are still stuck with Roshi, while Goku is off training at Karin's
>the Humans train with Karin, meanwhile, Goku is training with Kami already
>the Humans train with Kami, meanwhile, Goku is training with Kaio already
Goku always had a head start, but even with just Karin training, Kami was impressed by Yamcha, Piccolo was impressed by Krillin, and Tenshinhan was able to inflict pain on Goku and make him try somewhat.

On top of that, the humans never make use of the Rosat or Vegeta's gravity room. Tenshinhan outright rejected the Rosat because he never thought he would measure up to Cell. They can't get any stronger if they literally never try, but the fact that they DID get as strong as they did each time they trained with a martial arts god shows they always had huge potential.

I think Namek was unfortunate for Yamcha and the Crane students; that was their last shot at really doing anything. Toriyama had the opportunity to bring them to Namek up until he made it so the balls could only bring back one Z-Fighter at a time. On Namek, you could have them show off the fruits of their training, and Namek was really a small window of opportunity where their newfound strength could have been somewhat relevant. They were fucked Android Arc and onward.

Tenshinhan had some small little moments with the Shin Kikoho in later arcs, but that was about it for non-Krillin fighters as characters. It's a shame because they had potential; they grew many times stronger than Goku did under the same master (Kami), but then they DIDN'T use RoSaT, and they DIDN'T use the Gravity machine for training. Then don't try anything more potent than their normal training because they know it's pointless.