I read with interest this link which discusses the goods and bads of having so many denominations. It is good because people sometimes are more comfortable and take ownership of a smaller group. It is bad because denominations point to the “errors” of others and make it look like nobody really knows what is the “truth”.
Add to the denominations thousands of unaffiliated churches. It could be said each of these is a “denomination” unto itself. All this variety when, as one commentator said, there was only one church at the beginning.
While there are libraries full of histories plotting the origins of denominations, my guess is there are just a few very human reasons for all the variety. They have to do not with what is in the Bible but with human nature.
There have been and remain many countries in the world. Not too far back there were many more countries in Europe than there are today, before that tribes. Within these countries are a variety of groups with different ethnic heritages. Within the ethnic groups are subgroups who do not see eye to eye. Within the smallest unit, the family, people often do not get along.
All this variety must be the source of the many denominations. The theology and “error” would have come along later after the splintered groups had time to write down their thoughts.
Because it is human nature to “do your own thing”, we can look forward to many new denominations and unaffiliated churches.