Saru? The one who came up with the plan to strap a warhead to a worker bee and have someone go on a suicide run to blowup the ship? The one who then voluntarily said he'd find the weakest point on the enemy ship so they could bring down the whole damn thing? Is he skittish? Yes, that's him fighting against his natural instincts. This is star trek not star wars, characters aren't 2d cardboard cut outs where they only have one character trait and act according to that.
He hasn't fought any natural instincts. Coming up with a plan and executing it are totally different things. Especially from the relative safety of a console. It's like saying internet trolls are brave.
I'm not saying he's a bad character. If you want to use Star Trek characters, he may very well have a Barclay type of arc where he's shy and skittish to begin with, but ends up being less skittish, but learns to overcome his fears. And Barclay was one of my favorite characters.
But he's nowhere near as cool as the other aliens I've mentioned. And right now, he doesn't strike me as anything special. But it's still too early to judge him or this series in general.