Only your DNA can give clues Ed, all else is speculation or assumption.
No real relationship to the Jones family until after he married. Maybe after years they thought of him as son and his children were a bonus, they were childless after all. Looks like he looked out for them when older and the boy they adopted.
If Betsy was his mother, she was only around 17/18 when he was born. It could be a childhood sweetheart or as you say someone from the pub.
Maybe build a separate tree for the Jenkins/Mansell family and pad out with extended family. Then go looking to see if any matches with your DNA.
I mentioned pro tools as just finished a month myself. Interesting how the small matches can help make sense of some family lines. Ancestry only show those shared matches 20cMs and above without it.
Good luck
Cas
