"Have you come" / "are you come" are present perfect construction, in question form. Early Modern English used forms of "to have" (have/has) and "to be" (am/is/are) as the auxiliary verb, possibly with a distinction of meaning between the choices. But using "to be" has gone out of style. It crops up in old literature, or new literature trying to sound old.
Old German has ties to Old English. In modern German, most verbs use a form of "haben" ("to have") (habe/hast/hat) to make present-perfect, but a few use "sein" ("to be") (bin/bist/ist/sind/seid).
The Wikipedia article on present perfect gives several examples using "to be" that are not in question form.
"Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil." –Jesus
(Matthew 5:17, KJV)