Rome vs barbarians over rated

Seems that research in this area illusive, many Roman writers over rated their conquered peoples to glorify their victory,perhaps over rating it. However, then you get writings suggesting that the barbarians were really cowards and cannot really fight that well. Albeit the Roman fighters had an amazing infantry that was trained superbly but still must have had a natural strength and quickness advantage. (supposedly they they did not have the height of others...but they had to be 5 ft 8 in. to be in military service...Mike Tyson would have just qualified!) The Romans cremated their dead before they became Christians. So we have very little data to go on. The few examples we have indicates they were unsurprisingly heavily muscled and big boned. When the Romans were Christians they were not 'Romans' any more but a mixture of mostly German,Celtic ,Middle Eastern,N. African,Spnaird,Balkan and various others. The 'originals' the ethnic group that conquered the known Eurpoean world were an extreme minority by that time period and an were extremely ethnically mixed at that time.
However...the Romans were victims to superior cavalry and archers....Hannibal's and Persia`s cavalry for example. The Persians have been the only nation or tribes to really beat Rome in their prime. They did it by keeping away from Roman infantry with superior cavalry and bow. One account a Persian General destroyed a Roman army to almost the last man without having to go hand to hand with the Romans. He then let the few survivors go because of their amazing bravery. Europeans somehow always overlook the Persians as the fiercest of all Roman adversaries. They want to elevate the various European nations in this regard...but in reality the Romans handled all Europeans with ease while being greatly were greatly outnumbered ina all their battles with the Germans,Celts,Spaniards,Britons,Dacians,Goths and many others. Overlooked is the fact that the Romans conqured these people with a much smaller force and ussually suffered minimal casualties. Eurocentrics just strangely overlook these facts and down play the Persians at every step. History is always flawed by Eurocentric historians it seems.