I've always felt more safe on the trail than I do on a sidewalk, but your fear of the unknown is rational.
Wild Dogs...not much of a concern unless you are on reservation land, I've only run into dogs up on the reservations in the Northeast corner of AZ...a strong firm yell made them turn away though, so not much fear.
Javelina ...if you get between one and it's young, they will certainly charge you....they also like to do a little false charge where they run at you and then back away..
The only way to defend yourself from a snake would be not to mess with them, and if you do encounter one, ....
As for other humans...there's a whole crew here at HAZ that would recommend carring a gun, but I'd say that's excessive, pepper spray would work, but again, it's a personal issue for each person...99.9% of the time the people you encounter will be out there to enjoy the experience, just like you....so...relax! Have Fun and enjoy what this amazing state has to offer!