Yup i think you are missing some basics.
Open borders with only 1 AI resulted in no Juda spread, and also no diplo bonus with Joao and others.
He cannot attack you at pleased

Normally you open borders with most AIs, cept those who are hated.
Gives +2 over time, and getting pleased is very valuable.
Builder mentality stops many peoples from improving further,
as mentioned you cannot afford building health stuff or walls much on deity. If health matters, you might grow your cities too inefficient.
Or monuments with terraces

Every hammer investment should be thought over, those buildings do nothing for research or city development.
There are some more details, your units are not attacking that very good barb city.
Playing with fear often results from bad diplo habits as well, 3 AIs could be your friends while Ottos are busy fighting Mansa.
I believe more can be learned from poor starts, where every tile or hammer is considered & valued.
You might not win, but can adopt good habits.
I would not play with HC and gold mines for learning.