Fun fact! Carthage and Rome actually signed a treaty of friendship early in their history! Not only that, but chainmail, used by the Romans, actually originates from Celtic peoples, and was sometimes known even by the Romans as lorica gallica - 'Gallic armor'.
Fun speculation! The Celts were probably living better than the Romans in this period. The Romans, during the Early-Mid Republic, had very few of the architectural marvels we associate them with (except the sewer), and Rome itself was never a very... well-planned city. Farmers in mud huts sharing rooms with their animals vs. Farmers in mud huts sharing rooms with their animals, but with a sparse enough population to enjoy hunting in the surrounding woods?
Life is good!