Every organism manipulates their environment in some way. The ones that can manipulate it in a way that allows them access to more resources than the others will out compete the ones who don't.
Evolution doesn't really work like that. It's just a low bar that everything has to cross from time to time. Being a specialist, very advanced hunter is in no ways better than a dumb jellyfish that spawns billions of offsprings.
That is incorrect, dolphins are unlikely to evolve hands and humanoids evolved hands before they became intelligent (probably to grab branches). It was very lucky that a good brain evolved in a body that already had hands.
> very lucky that a good brain evolved in a body that already had hands.
The other way around: hands adds evolutionary pressure towards becoming more intelligent. (The ones that understand how to use their hands and tools better...)
Dolphins do have organs with which they pick up things like rocks or shells and they are able to give them to each other.
They use their sexual organs as "hands"! Both males and females.
In the tree of life brains are correlated much more strongly with locomotion than with hands. The moment you need to do (inverse) kinematics to plan an immediate action, and to plan sequences of motions, and to plan a hunting or fleeing strategy, is what put pressure to evolve brains, static lifeforms can be very complex and have complicated genomes, but brains you wont find in them...
If elephants were carnivores, with their trunks, they would have evolved efficient methods to hunt, and would probably be the dominant species on the earth landmass surface.
All this without hands.
The fact that they are vegetarian gave us the chance to do that evolution ourselves.
Looking at this planet, it's less likely to happen.
Maybe high density (water) makes tools less useful, and thus hands less useful,
since you cannot move a tool particularly fast under water, compared to on land.
I suppose you've tried throwing a stone underwater -- compare with throwing on land.
From this seems to follow, that creatures with human like intelligence, are less likely to appear, if the density of the liquid or gas surrounding them, is too high. (Dolphins are bright but not that bright.)
Imagine a planet with highly intelligent whales who have no way to manipulate their environment (hands) and no need to.