Both timelines:
- Gohan was dragged into the Raditz fight by Raditz. He was dragged into the Nappa/Vegeta fight by Piccolo. He was never supposed to fight Vegeta/Ginyu/Freeza on Namek, that was just shit that happened while he was trying to revive his new dad (Piccolo).
- On Namek, Freeza curbstomped everyone, no contest, including Gohan, Piccolo, Vegeta, and Goku. Once Goku went SSJ, he curbstomped Freeza, no contest. Freeza was a whole league above Saiyans, while SSJ was a whole league above Freeza.
- After SSJ Goku saved everyone, they got transported to Earth, while Goku dipped to go learn Instant Transmission. Vegeta moved in with Bulma as he trained (but never reached SSJ) and waited for Goku, while Gohan went back to school.
- Cyborg Freeza arrives on Earth looking for revenge.
Trunks' timeline:
- Goku jumps into the Cyborg Freeza fight using Instant Transmission, and kills Freeza. Everyone is once again singlehandedly saved by their hero SSJ Goku.
- Vegeta and Bulma have baby Trunks.
- Goku dies of a heart attack.
- The Androids arrive.
- Everyone else gets killed. Gohan and Trunks, the two kids of the group, are the only survivors (and Bulma).
- Gohan manages to learn SSJ on his own. It's not enough. He gets his ass kicked and loses an arm protecting Trunks.
- Gohan dies, and Trunks learns SSJ. It's not enough. He gets his ass kicked. He gives up and agrees to use Bulma's time machine.
Our timeline:
- Trunks wonders what's taking Goku so long to stop Cyborg Freeza, so he jumps in and kills Cyborg Freeza instead. Goku was apparently waiting for Trunks while Trunks was waiting for Goku.
- The sudden appearance of a second SSJ (Trunks), along with his warning about the Androids, pushes Vegeta to unlock SSJ for himself too. Vegeta was somewhat okay with Goku being the Chosen One, but if SSJ is something that can be reached by multiple people, then Vegeta has to reach it.
- Goku has his heart attack, but survives.
- SSJ Vegeta tries playing the great hero but gets his ass kicked.
- Vegeta and Future Trunks train to find something more than SSJ, as do Goku and Gohan (after Goku pushes Gohan into SSJ).
In Trunks' timeline, Gohan was in no position to take on Freeza, let alone the Androids. Not until he grew up and learned SSJ, but by then it was just him alone, and Androids have repeatedly been shown to be able to beat SSJs, and the Androids had a two-against-one advantage over Gohan. In our timeline, with four SSJs, they still decided "Yeah, we should probably find something better than SSJ before trying again."