I think the premise of your discussion, that the shootings were "perpetrated" by Rittenhouse, is not quite accurate.

I've spent a lot of time reviewing the Rittenhouse footage and reading the relevant laws, with findings detailed in this comment, and what it seems like so far is his actions were reasonable self-defense.

Specifically, Rittenhouse was being chased by an angry mob, one of whom had just pulled out a gun and fired it into the air. To Rittenhouse, this would be indistinguishable from one of the mob actually shooting at him. When you're being chased by an angry armed mob that isn't breaking off despite your attempts to flee, at that point it's reasonable to believe you are going to be gravely injured or killed, and the only way to prevent it is to shoot back.

The only things that could undermine his self-defense claim would be:

1) If the prosecution could show Rittenhouse did something to provoke the mob to attack him. I haven't found footage of what happened that caused the mob to start chasing Rittenhouse, so I can't say for sure that he didn't do something that would reasonably provoke them here he could use that as an excuse to shoot them.

However, based on some other information I would guess not. Specifically, the people chasing him that he shot all had notable criminal records (one was a convicted sex offender, another had been convicted on at least 2 separate counts of (serious) domestic abuse that included strangulation and false imprisonment, and the 3rd had been charged with felony burglary and a few other crimes, and at least one of them looked really agitated already when filmed earlier in the night confronting the militia Rittenhouse was a part of. It seems more likely that they were just aggressive men that started chasing him because he was separated from the group or something along those lines.

It could turn out I'm entirely wrong and Rittenhouse did do something to reasonably provoke them. Under Wisconsin state law, since he was fleeing he would have regained the privilege of self-defense, unless it can be shown that he provoked them with the intention of creating the situation where he could legally use lethal force.

2) The less likely reason his self-defense claim could be undermined is if the prosecution can convince a jury that either his belief that he was under the threat of serious bodily harm/death wasn't reasonable under the circumstances, or that his belief that lethal force was reasonably necessary to prevent the harm wasn't reasonable.

I don't see this one being the way they get him, because Rittenhouse was being chased by an angry mob, and right before the first shooting one of his pursuers pulled out a gun and fired it into the air, which to Rittenhouse wouldn't be distinguishable from being fired at.