Left wing people, how did the Tudor English kings in battles such as Agincourt, use the England flag to welcome everyone in the world?

They used it to assert national identity, particularly after the reformation when all other flags were banned apart from the St. George flag. Also it wasn't about welcoming everyone, more about diplomatic alliances and trade agreements that would benefit England and Wales as a whole.

They used longbow arrows to "welcome" people.

Step into my entryway. Don't mind the zigzag of pikes. Just decoration.