Your disagreement, from what I understand, seems mostly to stem from the fact that shrimps have less neuron than humans.

Did you check RP's piece on that topic, "Why Neuron Counts Shouldn't Be Used as Proxies for Moral Weight?"

https://forum.effectivealtruism.org/posts/Mfq7KxQRvkeLnJvoB/why-neuron-counts-shouldn-t-be-used-as-proxies-for-moral

They say this:

"In regards to intelligence, we can question both the extent to which more neurons are correlated with intelligence and whether more intelligence in fact predicts greater moral weight; 

Many ways of arguing that more neurons results in more valenced consciousness seem incompatible with our current understanding of how the brain is likely to work; and

There is no straightforward empirical evidence or compelling conceptual arguments indicating that relative differences in neuron counts within or between species reliably predicts welfare relevant functional capacities.

Overall, we suggest that neuron counts should not be used as a sole proxy for moral weight, but cannot be dismissed entirely"