Hi Kate
1st - There is definitely that many churches but not all are Protestant and thus exists a fundamental divide. There are churches that reject the full authority of scripture such as Christian Science, LDS. Then there are churches that do hold to scripture, but have a false gospel and/or false god (i.e.: Jehovah's Witnesses, Fundamentalist Church of Christ)
2nd - The churches that are Protestant are ones who hold to the 4 Soli.
Sola Fide
Sola Scriptura
Sola Christus
Sola Gratia*
Soli Deo Gloria
These churches includes:
Lutherans, Baptists (most that are non-denominationalists are Baptists in origin). Presbyterians, Mennonites, some Amish, Church of England/Anglican, Congregationalists, Methodists (those who still accept the authority of scripture),
From what i can tell, it seemed that the most prevailent church has been the Baptist type churches as many of such churches teaches adult Baptism (not strictly however, as they would baptise anyone who've made the confession of faith, and is determined if the decision is true).
The division between these churches are not fundamenal divisions. We may differ with respect on, for example, Free Will vs. sovereign Election*, Pedo-Baptism vs. Adult Baptism, or Pre, vs. Mid, vs., Post Tribulationism, but by no means do they determine the salvation of the believer.
Fundamental/Primary Theology, which includes the 4 Soli and the Doctrine of the Trinity, are the teachings of scripture that saves
Secondary/Periphrial Theology,, are important doctrines but are ones that do not save. It is of such importance that gives reason for them many Protestant churches, but by no means divide brothers and sisters, spiritually.
Tertiary Theology are doctrines that hold the least of importance such as found in doxology (what is worship, traditional vs contemporary worship, how worship is to be done), eschatology (End-times),
