Why do humans seem to be so much weaker (physically) than nearly all animals that are around our size?
Asking “why” is begging for an answer that infers intent. Humans did not “choose” to be “weaker”, if indeed we are vs. the rest of the animals around our size, just like we did not choose to be “stronger” than all the animals that are much smaller than us. And indeed, the vast majority of animals that ever existed, were smaller than us humans, including our ancestors.
This is an infographic with an estimated % of biomass distribution on Earth today:
The % of animals that are larger than us, if we exclude the livestock that is by any practical sense completely subjugated to us, is practically insignificant.
So…in hindsight, we are very, very strong vs. the vast majority of animals, and immensely more successful than the few animals we are - in the narrow sense of strict physical might - weaker than.
Natural selection has chosen wisely that we were larger than insects. That was more than half the battle (again, no buttons were pressed, no crossroads were picked, there was no agency, I am just entertaining the “why”).
