We don't "know" that infection confers any sort of lasting immunity, but there's zero reason to believe it doesn't give you immunity at least for a few years.
This is all rooted in the media narrative trying to scare people to stay at home "you could catch it over and over again". It's not science, and it's counter productive.
Well, it's not science, but it may be productive. A lot of people will hear "it's not so bad" and "healthy people should get it and get over it", and go out and make others sick (including people that could die or be hospitalized).
It's not science, it's crowd control. People don't exercise good judgement reliably, so that might be counterproductive.
This is all rooted in the media narrative trying to scare people to stay at home "you could catch it over and over again". It's not science, and it's counter productive.