Small groups and singletons are not yet conjectural for origins, more results are needed. This includes "English"-based men and the Northern US Slayton results.
Two groups of these men. "Arthur and Rachel" and "Carolina" each appear to descend from two separate common ancestors, one assumed to be related to (directly from) an Arthur who married a Rachel. Some are provable to Arthur & Rachel by paper records, some are mysteries. Any of these men could be from (unknown) male siblings of Arthur: with the present information, it appears that most of the "Arthur & Rachel" men come from Arthur or from the (unknown) father of Arthur.
The "Carolina" group is unclear for a single common ancestor, but appear to be from siblings or first cousins to one another.

It has become a convention to consider an earlier John Sladden in Virginia records to be Arthur's father, but we must remember that males named Abraham and William were in merchant records in the 1730s, and appear to be adults at about the time of the birth of Arthur & Rachel's first recorded children. We have no list of children for these men, but in 1766, a John Slatton witnesses a document for William Sladen in Albemarle Co VA and an Abraham is clearly a landowner in 1751 Albemarle Co VA. In 1790, a Major Slaton is enumerated next to Abram Slaton in Greenville SC census. All of the men in the "Carolina" group appear to descend from a John or Major or a George, all of whom later settled in NC and then SC, and do not match the haplotype of Arthur who married Rachel. Therefore, we cannot assume that the first John found in 1711-1720 Hanover VA is necessarily the father of Arthur (I-P372) or William or Abraham (probably I-M253). 
A large family based from Thomas & Hannah Slaton/Slayton of Massachusetts needs more testing results, as do the English-based lines.