'Messiah' or 'Lord' was applied here as a term of respect to a benevolent leader. 'My Lord' is also a very common term in British history; even to this day. And I do not believe it is used to denote a HOLY character. Do you?
Messiah is annointed by G-d, the one sent by Him. It is mostly used now in the context of
the Messiah, but that is not the only application of the word, as you can see.
Lord is the one that rules over you, whether benevolent or not. To say, "My Lord" is to say, "My Maser" and place yourself in the position of the one ruled by the Lord. IN particular, that is what religious people do with respect to G-d, so the word is used in that context as well.