I hear what you're saying, but attempting to murder someone is still attempted murder, no matter how half-arsed the attempt. Stealing a bottle of water or a candy bar is a lame act of theft, yet theft it is.
So, the record is absolutely clear that Trump, upon numerous occasions public and private, claimed he won the election and engaged in activities to undermine the result and maintain his presidency (some of which are arguably illegal). The 6th Jan demonstration was explicitly in support of Trump and his view that Biden's presidency would be illegitimate, and Congress needed to be "persuaded" of that and to instead affirm Trump to a second term. That is our base context, and it's a whole lot of intent.
In terms of a lot of the communications unearthed by demonstrators are a lot of rhetoric of threatening legislators of even killing some of them, plus strategy and planning for how to deal with police, Congressional security, etc. Now, that's not every demonstrator by a long shot, but it does indicate again give us some idea of intent, premeditation, etc. to overturn the election result. However, at the point an individual who was not part of these conversations, there's principle like "joint enterprise". They surely all knew the sorts of things being talked about (much from Trump himself if nothing else).
It is perhaps harsh. I'm sure a lot were bemused to have got in there and just felt like looking round and stuff rather than really activrly trying to attack Congress... but even still. I really don't think it can just be viewed as a unusually high profile trespass. It's certainly not a "political prosecution". It was a huge and explicit attack on a branch of the US government.