Saying he was the Messiah in and of itself was subversive to established thought.

They had a long long history of people making claims to kingship based on having a supposed message from God. Like Jeremiah which is clearly the story it was plagiarized from. Additionally, the narratives are contradictory on what exactly he said while interrogated. Which makes sense if you are just making it all up.

The Jews at the time thought the Messiah would come in clad in armor, sword in hand, on a white horse, come to slay their enemies.

Citation needed. Please use the Talmudic prophecies and the references of Josphius to back up your claim. There was a wide variety of different messiah prophecies in circulation at the time. Some of them yes we're closer to warlike image you made, copying from the Maccabees and Samson. Others were much closer to Isaiah and Jeremiah. Just a guy going around preaching.

Instead he rolled up humbly on a donkey

Not according to Gospel of Matthew. In the Gospel of Matthew he was riding a horse and a donkey at the same time. The author of first Gospel liked to double stuff, made his lies easier to swallow I imagine. Or he just didn't know Hebrew and Aramaic and misunderstood the last sentence repetitive structure of the poetry.

talking nonsense like “love each other, treat others kindly”

Like here?

Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword.

-Matthew 10:34

Also all the nice stuff he said was from Hillel or Proverbs.

Wanna try again? Or just admit that he is a fictional character that con artists poured Jewish history and thought into.