Jesus was one of these three things: God, liar, or lunatic.
Well, he certainly wasn’t God. He may have been a liar, but perhaps not in the bad sense of the word.
In those days, the quickest, easiest way to get the people to follow you was to claim that you represented God, that you spoke God’s word. If Jesus had not claimed that, he pretty much would have been ignored. Whatever progressive ideas Jesus put forward (and he did put forward some progressive ideas, such as wife is her husband’s servant, not his slave, or his ideas of forgiveness, charity etc.), would have been ignored.
Since he claimed that he was the Messiah, he received the following that he wanted, to spread his message. Indeed, the politicians use the same techniques today. Some of them (mostly Republican) claim to speak for God. They all appeal to patriotism, equal rights for everybody etc. If they didn’t do that, they would not get a hearing.
So Jesus may have been a liar in the sense that most politicians are liars.
Also, I can imagine many other possibilities. One is that he was a charlatan (that goes with being a liar I suppose). Another is that he was just a poor carpenter, and Christians built a religion around him out of whole cloth, and Jesus himself may be surprised if he saw all the religious trappings around him today.
Yet another possibility is that he never existed, that he is a composite of Vishnu, Mahesh (Hindu gods), Horus etc.
So I can think of many possibilities besides God, liar or lunatic. And except for God, I wouldn’t rule out any of them.