Why were the English able to defeat the french early battles such as the one at Crecy?

No not because it was because the English had new and approved weapons such as the long bow which was faster to load while the french had longbows which could take a 100 years to load( being sarcastic here)

There are a few reasons.Firstly, they had longbows which could fire up to eighteen arrows a minute.The French had crossbows which could only fir at around 5 arrows a minute.The English had a height advantage as well, which reduced the impact of the french cavalry charge, which made easy prey for the longbowmen.