I would have never thought Kelpian meant that they were actually just Kelp farmers. To be honest watching his people, wandering around, farming, foresting, tenting their planet is so serene that you wouldn't ever have thought that their species had developed a sixth sense.
It is as if they developed as a species to become a prey for others to feed upon. That there is no other greater honour then being the meat product for someone else. But when you see them going to through the Harvest celebration, it is a ship or alien device that comes to collect the sacrificial people. There are no species that actually hunts them.
That is strange as you would think that a species that has a sixth sense to sense on-coming danger would have grown the fighters in their civilisation. But all the Kelpians know is the same ritual that never changes. They don't even hunt.
In our eyes their civilisation is a utopian paradise that has dark twist which planet wide religion brought in. It does not explain the evolution. Not in biological terms. Not in the we know how the science works.
But it is interesting that Saru's species goes through all the same emotions, even anger and rebellious thoughts for being a member of utopia. I really loved that Star Fleet went beyond the protocol as Georgio broke the protocol as she collected Saru as a member of prewarp society, leaving behind all that is so wonderful in his world.
In a way Saru's story is the same as Luke Skywalkers, with the exception of him not blowing up Deathstars.