The Constitution never protected libel and slander. An activist Court in the 60s invented a new “right” for the press.
Libel was subject to both criminal and civil penalties before Brennan gutted those laws.
First, I said that there isn't a Constitutional check on lying. Libel and slander are more than just lying. Second, on your points, then there should have been a qualifier in the First Amendment if that was the Founders' intent. Or, there should have been scores of such cases from the early period of the nation. But there isn't, and there aren't. Indeed, Jefferson's quotes on how much he detests the press' lies, compounded by the fact that he never sued anyone on libel grounds, support the assertion that libel and slander, while detestable, aren't banned forms of speech. Now, to be sure, there are such cases but the bar is high.