posted 03-16-16 11:55 AM EDT (US)   
This was a fantastic idea, and I'd love to see it as strategy game but I would like to add some new suggestions.
One, allow the British to have gunpowder units, I never understood the idea that the British never had guns in Age of Empires 2.
Two, If you are looking for new civilisations, You should add the Irish, they have a very interesting mythology and you could have heroes like Fionn mac Chumhail, Chu Chulainn and Oisin from Tir na Og.
Three, I was thinking yet again for the British that Jack (Jack and the Beanstalk) could be added for a hero. You could introduce a unit similar to the mountain giant from Age of Mythology as his monster.