Yes, I'm aware there are more gospels. There's one of Judas as well. And some other apocryphs. You have to keep in mind that old stuff always will change when a new religion is formed, it's normal. Old dogma's will be abandoned or assimilated to the suitings of those who shape what comes next. I also have my doubts with the decisions made in for instance the council of Nicaea but there wasn't a catholic church at that point. It formed out of those councils and developed later on to control the masses. So the leaving out of several books has not so much to do with that purpose at that point. It was mainly to create clarity I think.