Why local(section) lift coefficient(CLL) is higher near the wing tips compared to the root on untwisted tapered wings and untwisted swept(aft) wings?
For the swept wing, as you go out along the wing, each section of the wing is effectively flying in the upwash of the tip vortex of the section immediately next to, and inboard of it. So, each section has its angle of attack increased by all of the sections inboard of it. The root section, of course, does not have anything inboard of it, and the tip section is affected (to at least some extent) by all the sections inboard (and ahead) of it.

Birds fly in V-formations to take advantage of this effect. Each bird is flying in the upwash of the tip vortex of the bird ahead and toward the center of the V, and is thus "flying downhill" aerodynamically. 

But, that upwash increases the angle of attack, and the effects add up as you move outboard, until they reach a peak effect near the tip.

You can really see this on hang glider wings: if you stand next to one as it's about to take off, you can see the tips appear to be at a negative incidence relative to the wind, and yet they are lifting, because the wing sweep increases their local AoA.