NO, it is not a threat of violence. Make America Great Again means just what is says. But if you never thought America was ever great, then maybe you will never understand the meaning.
Do believe that all violence (use of force) is bad, or some violence moral and necessary? Would it be okay to use violence against a man trying to rape a little girl to save the child? I'm sure you would use violent force to save a child, I assume this because I am certain you are an ethical person.
A fist can be used to offend, or used to defend. I display as a symbol of defense. Same would be said about all of my guns. I don't have them to harm or commit crimes, I am armed to defend against unjust violence.
You are really reaching. And it is not my job to worry about the tender sensibilities of people who are not white, not straight, or not born in the USA. If my white skin, or my non homosexual US born self tends to bother some people, that seem like a 'you problem' not a me problem.
I always saw it (the Black fist) as a show of solidarity.
My Maga fist, you can assume whatever you like, but show me where I have ever advocated criminal violence, because it never happened.
I think we are done here. You are triggered by your false assumptions and wild imagination. Try to get a grip.