Hm, while I completely understand wanting the honeymoon period and romance of an engagement, at this point you are connected far more than if you were married. A child will leave you far more connected to a man than a marriage would, as you can end the latter.
It does sound like he has settled into a married life without really going through the motions. His response, while absolutely rubbish to hear, really doesn't surprise me. In his eyes, he probably sees your child as a greater connection than a marriage would be, and I completely agree. Could it be that there are other external financial pressures (from potentially your young child?) which are making him hesitant on shelling out a lot on a ring when in his eyes nothing will change?
At some point, if you want to get married to this man, and not just the idea of a wedding, then sit him down and say you want to get married, not you want him to propose. If he agrees, great, you are engaged and can start planning a wedding. If not, you know where you stand.
Tradition only gets you so far, and technically you've already thrown that out the window by moving in together and having a child.
I do feel for you about wanting the spontaneous romance, but I think some guys don't have it in them or don't think about it like we do, and need a third party dig.
I told my OH that I would not buy a house with him unless we were engaged- effectively an equal commitment. He did get a ring but then didn't propose for months, so I actually made plans to propose to him! Funnily enough he did so a few days before my chosen proposal (which I did anyway) but I was fully on point of proposing to him. And actually, it was really fun to do so.
I agree with your earlier post that you want a great marriage, which does not necessarily translate to a great proposal. At the end of the day it should be the man you want, not the sentiment of a ring he puts on your finger. He wanted a child with you and to me that proves his commitment.