if you consider that "having" the right person on the leadership was considered crucial to please the gods and ensure good harvests yes altough normally the growth of social stratification happened when troubles ocured kings and nobles have always been born out of the ranks of heroes who "save" the people during times of strife

you have as examples the american civilizations where after a few traumatic events sacrificing people became routine or the bbylonian myth/tradition of picking a new king who would rule for 15 days to be sacrificed later so the old king could return to the throne guilt free of any sin towards the gods

not to mention ofc the way that religious high strata was always involved in the pickings of who gets what namely higher lords and kings positions since fertility and survival have always been associated with apeasing or getting aproval from the gods sooner or later it became the basis for kingdoms and hereditary hierarchy since having the right "special" or "divine" blood was essencial

not to mention the godkings like in egypt or the highpriest king of ... todays england the queen or king are the supreme ruller of the anglican church ...

what must be understood is that as new agricultural practices became prevalent into lands where before they where not used (in our case iberia and gaul and britain particulary the creation of new farms or concentration of lands who allowed for better productivity ) the increase in food allowed for populational growth but not better wealth division

amongst the lusitanii/gailicii the practice of having only 1 heir was and still his wierdly enough normal so all other less suitable sons had to go and find a living somewhere else thus the constant complaints of caesar that the lusitanii roose in rebellion every year when the reality was that they where driven out of their homes so as not to split the land given some weapons and goodluk prays and told to carve out a new life as mercenaries tradesman or whatever but his family lands belonged to their brother

so the appearance of farming into iberia created more wealth but not better wealth distribution in gaul the more wealth was available the less people had acess to it same as in rome winning the punic wars and the influx of money that was gained by trade only increased the depletion of roman citizens availble to be recruited for the legion more people but less qualified people since the small and medium land owners where swallon by the big oligrchic families

also i´ve read up some articles on mountain regions farming and it´s not impossible so even in germania and the luigii regions there was room for the appearance of small farm or at least small plot of land in front of their houses to complement the pastoral lifestyle wich altough increasing the available wealth wasn´t suitable for big land industrial farming so you get a better distribution of wealth (i recomend searching youtube engineering an empire the inca agricultural practices )

the celtic practices in gaul and britain also saw some technological evolutions that enabled better yelds on their fields so even if there was a decrease in the productivity overall due to the climatic events the way that new fields and new areas where being braved for farming combined with new technologies and the beggining of the appearance of larger scale industrial farming more then compensated for it imho (for instance many archeologist have proven that the kelts could get more out of their small farms per plot then the romans but the romans compensated that with massive slave work and sheer scale )

but thats just my interpreation based on my very incomplete knowledge of what was going on back then and it´s a macro view of the events some places might have had diferent developments also my knowledge expands well into the 1st century so much of the information and interpretation might not be pertinent to the 3rd century bc altough it becomes so as we progress forward