Cousin Spren

[Eki]

Adonalsium didn't shatter on Roshar, so I doubt any potential splinters from that event (except actual shards, if you count them) ended up there. I think Adonalsium left spren on Roshar when he designed the planet, as a part of the ecosystem. The WoB from @The One Who Connects supports that.

And we know of humans that weren't created by Adonalsium as a whole (Mistborn spoilers):

Spoiler

The humans on Scadrial were created by Preservation and Ruin, and had a tiny bit more of Preservation than Ruin in them.

That still makes them have a piece of Adonalsium in them, but not equal amounts from all shards. And from what we can tell, this doesn't necessarily change how they work - they still act the same as any other human. The only difference is that some of them can access specific kinds of magic that others can't. (Which probably means there are other kinds of magic that they can't use, but humans "of Adonalsium" can. Who knows though)

We don't actually know the full origins of humans on Roshar. I think they are refugees, possibly from Yolen, who Cultivation and Honor took with them to Roshar. But it's also possible that these humans were created by the two shards.

And I wouldn't say that humans are the "blueprint" for sentient life, that bringing something closer to Adonalsium necessarily means making it "more human". More sentient, perhaps, but there are many sentient species in the cosmere, Listeners included.