When I was in college, I found that the big, thick textbooks often confused me. Why? Their writers immediately focused on the trees So, I could not see the forest. That is, many of the writers of those big, thick textbooks understood their subject, but they did not know how to teach to someone as thickheaded as me. Fortunately, the bookstore sold books written by better teachers who knew how to get the basics across before they dove into the weeds. Once I read one of those books I was able to make sense bigger, thicker, textbooks.
Salvageable is one of those better writers. If you want a good, basic introduction to Early Christianity, read his two posts. Here is the first one => https://salvageable04.wordpress.com/2021/07/23/early-christianity-part-one/.