The guy you said that Pacquiao won his 1st title from was the lineal champion at flyweight. You may never heard of the guy or think who cares about flyweights, but becoming a lineal champion is a very impressive feat at any weight class especially at 19 years old. That is a rare feat in boxing history to become the man of a division in your teenage years. So I wouldn't play that down as you're trying to. IMO that feat is one of Pacquiao's greatest accomplishments.