You might think that putting a spider outside is humane, but you are probably condemning it to death. Most domestic spiders are in the right habitat for them, whereas "outside" is alien to them. I lie about what I've done with a spider I've caught. I'll let it go into a corner or under the sofa, etc., or put it in the utility room or porch, rather than throw it outside. In the house they are feeding on silverfish and other little pesky things like that, and they won't run short of food. So leave them be. They are not just harmless, they are positively useful.