If you look at consumption-based emissions[0], China is at 7 t per capita, which is 8 t less than the US, 2 t less than Germany and about par with Denmark, Slovakia, and England.
0: https://ourworldindata.org/grapher/consumption-co2-per-capit...
Why shouldn’t the highest emitters not be the ones to reduce most?
I don't understand the "25 smaller Chinas" argument. China sets statewide emissions policies. That's a reason we pay attention to country borders here, rather than considering an undifferentiated mass of humanity as a map scatterplot.
Ultimately, the reason to point out the gap between China and Europe or North America is that if you concentrate climate mitigation strategies on the west, you won't actually do much to solve the crisis. Fair's got nothing to do with it.
1) China needs to cut more emissions in total.
2) The US/West needs to cut more emissions per capita.
But if both groups argue that the other group has to do their part first, or they won't act, then nothing will get done.