Thanks so much for the additional information.
It sounds like he was being protective for you...the one aggressive episode that you mention.
Just because a dog hasn't been socialized around children from puppyhood doesn't mean that they can't adjust and acclimate to them once they are introduced into their lives.
And, your child is going to be perceived differently than a 'stranger" child would be. You don't want Wolfy to feel he's in competition with your son. You want him to be perceived as a member of his pack so there's no rivalry between them.
I would never leave a baby and a dog alone...Never!!! But in all honesty, you may be taking it extremes by keeping them totally separated.
I do think that there should be a Wolfy "zone" which is his sanctuary. Crates are excellent for this purpose especially since you have a small house. I don't use crates as punishment; I view them as a bedroom or safe haven to which dogs can retreat when they need to or where we put them when necessary. You're not going to be crating him all the time, only when you can't watch both him and your son. I don't believe he will resent it either especially if you give him a Kong (LINK
) filled with peanut butter to occupy his time or something similar.
As to the interactions between your son and Wolfy, they are obviously always supervised. I would encourage you to make sure he's not just "pretty reliable" when it comes to commands but "totally reliable" at least for the basics...sit, stay, come, down and leave it.
Have Wolfie on a leash, make him sit and reward him with praise and something really yummy, then have your husband approach with the baby. Perhaps just far enough away that your son can't touch Wolfie but close enough that Wolfie is associating a pleasant positive experience (food and praise) with your son. Training sessions of 5-10 minutes, several times a day would be best if possible.
It's not too early to teach your son manners around dogs either. While one of you has Wolfy controlled on a leash, and in the sit/stay position (being fed yummy treats), your son can touch and pet his fur. Lots of praise for Wolfy and using words like "gentle" with your son.
Share your attention with Wolfy when your son is around so he, again, associates a positive experience with him. Walk them together in a stroller if possible. Feed Wolfy treats in the back yard with your son present. Shared positive experiences in other words.
The humping he did isn't uncommon. This behavior has many sources and play or even dominance are likely in this situation. As disturbed as you might have been by it, I wouldn't overinterpret it at this point.
It sounds like Wolfie does have you figured out and he knows that you're anxious about him around the baby. But it sounds like he has a natural curiousity about him and would like to get to know this creature that means so much to you.
I think if you take it slow and are patient with the process, that you won't have to be as worried about your son's interactions with him.
I hope this helps ease your mind somewhat they both can coexist together with some basic precautions and positive reinforcement training. Deb