Sewing for Civil War reenactments has taught me a lot about fabrics. Since there was no nylon/polyester/rayon/etc. in 1860, and fabric labeling isn't all it should be, we run burn tests on scraps of fabric to make sure we don't have synthetic fabrics. Here are the results:
Cotton burns rapidly, with a good flame. Don't let anyone tell you it's fire resistant, unless it has been chemically treated.
Synthetic fabrics don't burn; they melt, leaving a sticky, clingy residue. This residue shows up on burn tests even if the percentage of synthetic fabric in synthetic/cotton or synthetic/wool blends is very small.
Wool, on the other hand is relatively fire-resistant. Sparks may burn a hole, but it's a lot harder to sustain a flame than with cotton.
Applied to backpacking--I wear nylon pants. They dry rapidly from just my body heat. Jeans are hazardous when wet because they take so long to dry (what's the last piece of clothing to come out of the dryer?). Wet denim also clings to the body, restricting movement.
I don't build fires either when backpacking. Here in the Pacific NW, the hiking season corresponds with the dry season, when open fires are not allowed. I also prefer being at high altitude (naear to above timberline), where fires are also not allowed.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey