I think your bike is fine for the type of riding you describe. I'm 5'8", 230 lbs, and my trail bike is a franken-mtb hardtail I cobbled together, with a Suntour XCR-MG fork (though I did put a considerably stiffer spring in it). Until I upgraded the drivetrain this winter, it was essentially your bike but with a 7 speed drivetrain instead of a 9.

Tire pressure and size are something to consider, as narrower tires or those with more air in them will absorb less of the impact. I generally run anywhere between 28 and 34 psi in 2.1" wide tires, generally starting at 34 and then letting some air out as needed if I don't like the way the bike feels/handles (especially in my front tire, which tends to slip out under turning at higher speeds if I've got too much air in it).

How are you approaching the roots? Do you just run straight into them, and are you seated or standing? Of course, you're always going to feel some of the impulse transfer through the bike, but generally when I'm approaching roots I'll stand up and pop up the front wheel right as I'm crossing, and then let my legs handle the shock of the rear. If there's only one or two roots and not much chance of faceplanting, I'll sometimes transfer my weight forward a bit as the rear wheel crosses to reduce the jolt some as well. If there happens to be a whole tangle up ahead where I cannot do what I've described above, I tend to slow down and just sort of crawl over them.

Oh, and a decent set of gloves will help absorb the shock to the hands, as will letting your elbows bend a little.

Just my opinion/experience, hope it helps!