For these reasons:
1) Chimps can speak human, but humans cannot speak chimp.
2) Chimps have incredible visual memory: https://www.youtube.com/watch?v=zsXP8qeFF6A
Their lack of "human-like world conquering" could perhaps be explained by other factors besides raw intelligence: missing written symbol system; possibly less dexterity for fine motor skills; "socially/morally crippled" by primitive tribalism over judicious cooperation
It strikes me we share some of the same flaws, but it would truly be funny and ironic if humanit's apparent "dominance" over Earth's surface were down to nothing more than: slightly more dextrous finger movements; writing; improved social algorithms - but that chimps (or orcas, or dolphins) were in fact far "smarter" than us, on average.
Also chimps cannot “speak human.” I think you misunderstand and exaggerate the attempts to teach human language to chimps.
Humans cannot “speak chimp” because chimps have no language for us to learn, at least not a language comparable to human language. People have learned to understand the vocalizations, facial expressions, and body language of chimps. Humans can grunt and scream and grimace just like chimps and we understand each other at that level.
If it were true, however, you'd expect animals to be able to beat us at poker or rock-scissors-paper if they had the capacity and motivation to play and unfortunately it doesn't seem to be the case.
https://www.livescience.com/60134-chimps-learn-to-play-rock-...
"On the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much — the wheel, New York, wars and so on — whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man — for precisely the same reasons."
-- Douglas Adams, The Hitchhiker's Guide to the Galaxy (1979), Chapter 23.