History session with Nala makes no sense regarding the bows and draw strength.
Humans have/had no problem creating bows with high draw strength - especially with war bows you'd get a high draw strength (or weight).
But the thing with draw strength is that you've got to actually have the strength to draw the bow! Being able to use a heavy war bow requires a lot of training. Otherwise there is a high chance to injure yourself and you couldn't even use the full potential of the bow.
Having the elves making bows with a higher draw strength than anything humans could create and then saying elves are physically weaker in every way compared to humans is completely contradictory. Elves couldn't even use human bows then!