Question

what is the meaning of art in Shakespearan English​

Answer 1

Thou is explicitly singular, where You admits a plural. Art is a conjugation of "to be", emphasizing use as a gerund. ThouArtGod, then, seems a less clumsy way of saying, "you, yourself, personally, here and now, are creating the universe." ... Not art in heaven, but art right where thou art.☺️

Answer 2

Shakespeare used a form of archaic English in his works that can be at times confusing, irritating, and downright silly. The words that I will discuss today are the archaic forms of “you.”