If the Harfoots aren't precursors to the Shire hobbits I'm not sure what the purpose is in having them on screen at all. Not to mention the appendices straight out told us the Harfoots are the descendants of Shire-hobbits along with Stoors and Fallohides. If they weren't going to have them be any relation to the hobbits of the blockbuster movies they could have just given them a made up name. No, they're definitely trying to draw a connection of some kind.
Someone up above re-posted "concerning hobbits" for which I am grateful. Possibly one development is for a Fallohide to take over as chief of this Harfoot band, which as was explicitly spelled out is something that often happened among the early hobbits.
Yes, I note that the Fallohides "tend to be fair" and friendly with elves while the other two subgroups are dark and tend to be ruled over by the Fallohides. Fantasy racism ... ugh.
That does look like an extremely likely way for this to happen; some proto-fallohide comes into contact with the elves, then comes back to bring light to the Harfoots.
Maybe this is why they included a dark-skinned elf in the story? Maybe the showrunners saw just how easily this could go into racism/colonialism and decided to add some diversity to take some of the bite out of it.
Respectfully,
Brian P.