The more cordage the better, but how about trying to build a shelter without using any at all?

Take a long branch, lay one end of the ground and support the other about three feet off the ground by propping it where a tree branch meets the tree. Drape a tarp over it or lay branches along both sides of it and cover it with leaves.

You can also make it free-standing using two equal length forked sticks to hold the end up to form a sort of lopsided tripod.