Human have had the motivation to invent things based on real strong needs, some based on mass population and hate for one another. Houses for shelter (we' can't survive the cold well without it), when populations grew large - cars for transport/logistics. Planes came later when populations were bigger and international business became a big thing, car engines made plane technology seem less alien. Humans wanted to kill one another, on mass, in big ways, that pushed for missiles. Missile technology gave way to rockets which can be used to go to the moon if need be.
Real needs gave the biggest drive to lots of base technologies and ideas. Once that framework was there, the world of hobbies could easily make use of it.
You could argue, we could just use caves for shelter with are semi hairy old bodies. But there aren't many useful caves. Population rises drove us away from that opportunity.
They think we lost hair due to moving from forests to savannahs to thermoregulate. I guess if we don't adapt fast enough, we desperately find tools as immediate measures. (Maybe one day we really will return to 'monkee'. )
Dolphins don't need shelter. They can survive well in the wild as they are. There population is stable, they don't fight for the good spots or space. Food is everywhere.
For us to survive well in the wild (as of now) without tools we would have to be very hairy again like monkeys for protection against the weather at least.
Basically dolphins never saw a strong need to decimate one another with their environment being plenty for their population.
Sadly, I think the only reason humans have loads of gadgets verses other animals is due to constant stress and not just from the environment but from one another.