The Celts were far from primitive barbarians. In fact, the Romans adopted many technological innovations from the (Celtic) La Tène material culture in what is now Switzerland. This includes the gladius and spatha swords, the Montefortino helmet, the lorica hamata chainmail armor and the oval scutum shield. In fact, most of the armament of a Roman soldier was based on La Tène originals or Celto-Iberic ones.
Right? It's almost like every conqueror debases and dehumanizes the conquered.
I sometimes sit and think how different the world might be if Caesar was defeated in Gaul, and if the Roman State religion (Catholicism) hadn't spread a few centuries later.