Your point is exactly my point to a degree. Power levels aren't stagnant. And Goku clearly wasn't using the top end of his base SSJ1 form.
Kaioken base Goku could probably wash a SSJ Gohan.
The only significance in them going SSJ1 is because Gohan can't handle more than that.
Goku was toying with Gohan, playing his little "great saiyanman" game. You think Goku was going to go top end with Chi chi a few feet away from them?
I get it, Gohan has potential. But Gohan is a constant reminder in the series that talent without hard work is just that. Potential
Goku trains goten in base form because thats all he can handle. He trains Gohan in SSJ1 because thats all he can handle. He trains with Vegeta as SSJB because thats his level..
SSJ1 Goku would wash Gohan no hesitation, but he doesn't... Because that would be stupid. No matter how much of a dead beat he is.. Gohan got him with a slick little hit. Gohan is always getting caught sleeping...