Overthrowing a legitimate election is treason. There are probably 20 ways the overthrow was done. All treason.
Overthrowing a legitimate election is treason.
Leading Americans into the Capitol with the purpose of later mercilessly prosecuting them later is nasty and foul and quite likely a crime, but it isn’t making war against the U.S.
The Founders went to the trouble of defining treason quite narrowly, since under English/British law treason (and its horrible punishments) could and was used by monarchs and Parliament to go after anyone who greatly displeased them. Not unlike the treatment received/being received by the January 6 protestors.
What do you do about an illegitimate election?
Remember a number of states had their own investigations of fraud still in progress. The outcomes would determine the legitimacy of their electors. What many of the protestors wanted was a delay in certification pending state cases outcome. That is not an insurrection.