The concept of free speech is 2400 years old. Don't be one of those people that conflates that concept with the American first amendment which only blocks government censorship and is barely 200 years old.
Private companies, groups, and people can and do infringe on everyone's right to free speech.
Times have changed and the public square is dead.
And the right to free speech has nothing to do with you getting your ideas heard. It's everything to do with what you can and can't be prosecuted for, and therefore is irrelevant when we are talking about something like youtube which can't prosecute you in the first place. Even back then the law could have said something like everyone has a right to get their essay published in the newspaper, but it didn't, because you can imagine how that would quickly get ridiculous, and ultimately just like youtube newspapers were private entities, only they had even more influence and reach than youtube since everyone read them and took them seriously as the paper of record.
The US has no Public ISP, nor Public Speech Platform equivalent of Twitter, Google, Facebook, etc.