EU citizens have the same rights to welfare as citizens do in EU countries.
As far as I know in Germany at least you need 5 years residence before fully qualifying for welfare if you're not a German citizen.
They also have partial voting rights. EU citizens can be expelled only under exceptional circumstances.
So they can't vote in national elections as I said. You can be expelled or denied residence on health grounds or public policy grounds. Regardless, you can be expelled, as I said. Some government jobs are also not available to non-citizens.
It would be trivial - and desirable - to eliminate these restrictions.
You just state stuff as if it's true and must be accepted. This is just an opinion. Presumably if it were both desirable and trivial it would already be the case, no?
So, of which nation state was said peasant a "citizen"?
You can probably trace citizenship back to the ancient Greeks in one form or another, but you'll likely try and change the definition to have to be about nation states or some other narrow definition to suit your point again, so there's not really much point in trying to discuss it.
Because, in this specific example, antisemitism was the reason immigration laws were created in the first place. In other cases, other types of bigotry and xenophobia might have played a role.
This specific example was chosen by you, presumably because it was an example of antisemitism. I was thinking more like Ug and his gang in the stone age, but it doesn't really matter. Tribes\social groupings have existed as far back as we have history, who, how and when people are excluded is varied and nuanced but not everything is a racist or bigoted action.