But in reality Jesus didn't come as a lion but as a Jewish man who is allegedly crucified and had died. According to Jewish thought Jesus failed. To the Christian, he did not. The point I'm making is why a bipedal organism? The idea as Rival had put it is that humans are sinful despite humans not existing during the time of Adam we take the burden of sin. With that being said Jesus the only begotten son of God and by only we are talking about the only being in the universe that is a big title to have. Why a human is God's ONLY son is beyond me and considering there to be the potential of older and wiser creations why is God's ONLY son a human?
Well I think I've already answered that twice now. But let's rewind a bit as you seem to be missing some theology.
God the Son was, according to standard theology (Nicene Creed), begotten of the Father before all ages and subsequently, at a point in the history of mankind, became incarnate of the Virgin Mary
et homo factus est and was made man. So he was made man as a separate thing entirely from his genesis from the Father. And after his return to the Father at his ascension into heaven after the Resurrection there is no particular reason to think he would necessarily have to continue as a physical man. So his taking human shape may have been just one episode, which may not preclude his taking another shape for another similar purpose elsewhere in the universe.
In short, there is no reason in principle why the same God the Son could not also have been incarnate in an alien world in another form, to fulfil the same purpose for those creatures.