Under your definition, any act is “speech.” The purpose of the 1st Amendment was to protect political and religious speech, not to protect people video-taping themselves having sex and selling the recording. The liberals on the Supreme Court have declared that pornography is “speech” and thus gets the protection of the First Amendment. They have successfully changed the discourse on the First Amendment that even purported conservatives, like yourself, are convinced that it is speech.
You still haven’t explained when pornography became “speech” under the Constitution. And to answer your question, yes, we should employ the standards “of the day” (when the Constitution was adopted). That’s the correct way to interpret the Constitution. Slavery is now explicitly illegal because a constitutional amendment. If you want to pass a constitutional amendment declaring pornography protected speech, then it would deserve the kind of protection you are insisting it should receive.
Free speech is under attack and your position is a big reason why.
Everyone and his dog is going to have a difinition of what does and does not constitute “speech” protected under 1A.
You really need to think this through more carefully.