He is being prosecuted primarily on what he did not what he said to his supporters encouraging them to demonstrate. This includes putting pressure on officials to ignore the popular vote, organizing fraudulent state electors in 7 states, knowing spreading false information about the election, pressuring his vice-president to reject the election results in the Senate, and ignoring his own staff members that informed him that the demonstrators were becoming violent and he should take action. Even during the attack, he ignored pleas from his vice president. In addition the prosecutor will call witness from his staff and advisors that will testify, that he was well aware of there being no truth to his claims of election fraud yet he persisted in spreading the lies.
As I never tire of explaining to Democrats in the thrall of their own media:
It is not a crime to put pressure on elected officials to do things you want them to. There is a whole job of doing nothing but that. It's called "lobbyist."
It is not a crime to express doubts about the fairness and legality of an election. Democrats do it nearly every single time they lose.
It is not a crime to tell your subordinate how to do their job. Again, there is a whole job of doing that, called "boss."
It is not a crime to ignore your own staff. How could it be when powerful people often get contridictory advise from different staffers.
It is not a crime to ignore naysayers in general. Nearly every unusually successful person in history has had to do that.
In the unlikely event that they can "prove" that Trump knew the election was squeaky clean - ok, the impossible event, because it was not - it is not a crime for a politician to lie. If it were the hoosegow would be full of nearly every president we've had in the last fifty years.
Freedom of speech does not mean there will be no legal consequences. Deciding what is and is not protected speech is reserved to courts of law. And that will certainly be an issue in the Jan 6th trial.
Most of the trial is going to be about what Trump did and did not do, not what he said. However, his pattern of constant lies about the election and it's effect on the Jan 6th attack on the Capital will be an issue.
As I explained above, nothing that you described him doing is a crime.
Another issue that will be important in the trial will be Trump's intent. What was the intent of his actions and speeches? After the votes were counted and recounted, claims of fraud investigated, and the states certifying the election, the Supreme Court refusing to get involved, did Trump really believe there was any real legal path to overturning the election results. There was almost no chance of him legally stopping the federal certification in the House and none in the Senate. His only option would be insurrection which was exactly where he was headed on Jan 6th.
It strains credulity to think that an outgoing president wishing to start an insurrection would offer to send the nation guard to stop any potential violance and would tell his followers to be "peaceful and patriotic."
How many people have been charged with insurrection so far, and how many found guilty?