Just a few comments:
The Starting Nomadic Tribe concept is one of the first differences between the entire Civ Franchise and the new Humankind game that hit you: in the latter, everybody starts in a Neolithic "Pre-Era" as a wandering group of Hunter-Gatherers. So far, as of the last pre-game 'build' (the 'Lucy' variant that ran over the holidays) during the Neolithic you can wander the map, attack other tribes or animals (and get Food from both, implying Cannibalism as a Basic Human trait, but also allowing you to form more 'Tribes'), pick up Food or Science 'bonuses', and found 'Outposts' which give you limited control over territory. You cannot start an actual Faction/Civilization, start a City, or start researching anything (although the Science Boosts from the Neolithic will give you a 'running start' on your first research in the Ancient Era). When you have enough Tribes formed or Science boosted, you progress to the Ancient Era by picking your first Faction/Civilization.
There's a lot about this to like, but also a lot of limitations built into it that are directly contrary to the historical and archeological evidence.
First and foremost, the Neolithic saw a lot of cities founded. It was by no means simply wandering small tribal groups littering the landscape. In addition, a large percentage of the human population, even without starting anything resembling a city, had settled down and was not wandering much throughout much of the Neolithic.
Second and equally important, a lot of the early founded Cities also disappeared during the Neolithic: they were fragile, and food concentration technologies were primitive, and it didn't take much (a couple of years of flood, drought, locusts, etc) to make the city dwellers give it up and go back to wandering - frequently, to wandering over to another city or settlement. Loyalty was a pretty fragile concept also.
Third, a lot of Technology was discovered and exploited in the Neolithic. In fact, I could make a case that most of the early Tech Tree in Civ should be Neolithic - or at least, in the right circumstances, the possibility of discovering and using them should be pushed back to the Neolithic.
That, however, brings up the major problem that has stifled the 'wandering Civ' concept for over 20 years: IF as in Civ, all population growth and accumulation of Gold, Research, Production (and more recently, Religion) are linked to Cities, how do you get any of them without first starting - and maintaining - a City?
Humankind started a solution by allowing Food and Science to accumulate from on-map 'Bonuses' that could be discovered in the Neolithic, but then dodged by making none of the results from Science be applicable until the Ancient Era. That is, no matter how many Science Bonuses you accumulate in the Neolithic, in Humankind you don't get a single solitary Technological advance from any of that until the Ancient Era - after your first City is founded.
Finally, and connected to any Nomadic Start is the problem of Nomadic/Pastoral Civilizations: groups of herders who (for the most part) didn't found or live in Cities, but still made significant Technological advances (spoked wheel Chariots, saddlery and tack, Horsemanship, Mounted Archery, lost wax metal casting, etc) and had a major influence on neighboring 'settled' Civs and overland trade across Asia.
There are some characteristics of the Neolithic that aim at a solution, I think:
First, 'Culture' and 'Loyalty', as stated, are pretty Fluid Concepts. Populations regularly left or arrived in city or settlement concentrations, and a great deal of city growth was from immigration (voluntary or forced - slave raiding was a major activity among all the early cities, apparently) rather than Birth Rate. That's because when people first congregated in larger-than-family-or-clan groups (Cities) they also made transmission of epidemic disease dramatically easier in those groups: without immigration, no city could have survived for long.
Second, even before discovering agriculture (which dates back to around 10,000 BCE) people were living in Settlements that didn't move: good fishing sites along the coast or along rivers or near extensive marshlands full of fat waterfowl or migration routes of large animals - places where food was relatively abundant even for Hunter-Gatherers.
Third, Animal Domestication of the large 'food' animals is almost contemporary with the earliest Agriculture: evidence of sheep, goats, and pigs living with or near people in settlements also dates back to just after 10,000 BCE (and may be earlier: it is very hard to tell the difference between domestic and hunted sheep, goats or pigs from just skeletal archeological evidence).
So, for an instance, let's hypothesize a game in which you start around 10,000 BCE with a Tribal Group. Based on your surroundings, which might include Specific Science Bonuses from either Wild Grains (wheat, rice, etc) or domesticable Food Animals (cattle, sheep, goats, horses primarily) your Group might quickly develop either Agriculture or Animal Domestication - the two 'starting' Technologies. Whichever you start with, that will determine a lot about your settlement and technological pattern in the immediate future:
Agriculture as a basic Food Source will lead to immediate Settlement and development of Technologies like Irrigation (primitive) and, if you have a Draft Animal source (cattle, horse) to Plows, Draft Animals (a 'bonus' towards the Wheel) and, in the case of cattle, horse, sheep or goats, to Storage Foods - cheese and similar 'secondary products' that can be stored over the winter with dramatic results to your Population growth and health.
Animal Domestication will still allow you to form a Settlement, herding between grazing sites around the settlement within a day's walk or so. IF the domestic animals include Horses, early Horse Riding, accompanied by solid-wheel carts or travois, allow animals to be 'herded' over a much larger distance, and your Settlement can become a Mobile Settlement. Your mounted herders can also become Raiders using the extra mobility of the horse, but the technology to form Armies and fight effectively from horseback comes much later: there is no such thing as a Neolithic Horde, but there will be a possibility for such persistent raiding that you force other Settlements to move away, giving you access to more territory/grazing/settlement sites of your own.
Yes, the old 'Cain and Abel' or Farmer versus Herder dichotomy is a Real Thing since the Neolithic
Among the Technologies available (potentially, not Absolutely) in the Neolithic are:
Pottery - dates back to 15 - 18,000 BCE
Agriculture:
taro (26,000 BCE)!
potato (9000 BCE)
rice (9000 BCE)
barley (8500 BCE)
wheat (8500 BCE)
millet (8000 BCE)
Animal Domestication:
Sheep (10,000 BCE)
Goats (10,000 BCE)
Pigs (10,000 BCE)
Cattle (8500 BCE)
Horses (5000 - 4200 BCE) - intense debate on-going about the exact date
Horseback Riding (4300 BCE)
Wheel (solid wheeled carts) (4000 BCE)
Metal Working:
Copper Lead, Silver, Gold smelting - all 7000 - 5000 BCE
Metal Casting (6500 BCE)
Lead soldering to join other metals (5000 BCE)
'Secondary Foods' - Milk and Cheese production and storage (6600 BCE)
Plowing with draft animals (Oxen - cattle) (6000 BCE)
Irrigation - primitive open canal systems (5000 BCE)
Oh, and the earliest cities (Uruk, for one) seem to have originally collected around sites with Religious Structures already there, so Religion of at least a 'semi-organized' form was also in place in the Neolithic (and the Gobekli Tepe (9500 BCE) monumental site may be viewed as a Proto-City of sorts)
And another 'potential' Tech: Warren Field in Scotland shows evidence of being trhe earliest known calendar construction, aligned with the solstices and lunar ccycle and built around 8000 BCE
So, possibly add Calendar to the Neolithic Techs and some sort of Social 'Policy' related to Religion to the possible 'advances'
The requirement to form Settlements into Cities would also be Social and not Technological: the concept of Heirarchy, or someone in charge who is not simply the oldest family member surviving, seems to have been crucial to keeping a city working: sites such as Catal Huyok which had a population estimated at up to 2000 but no sign of any heirarchy (all dwellings the same size, no central granary, worship site, ceremonial site, gathering site) fell apart as soon as things got bad (in Huyok's case, a drought). Given the examples of the religious structures preceding cities that proved permanent, having a Religious authority in place first might also be a clue or at east a Bonus towards 'real' City forming.