You cannot possibly know that the vast majority of people who contract COVID-19 suffer "no lasting effects." Enough time hasn't passed to determine that. Moreover, that does not discount the fact that a significant number of people do become severely ill, straining our medical resources, and many do die, particularly the elderly. As far as the 1918 pandemic, cities across the country shut down then too...
And I read the articles you quoted - the articles aren't actually saying the 1918 flu virus is still with us. Their point is that descendants of that flu are with us, as over time the virus evolved into a less deadly flu strain. To your point though, we can hope that COVID-19 ends up behaving similarly, with the original strain falling away and becoming replaced with less deadly descendants. I'm not sure that will be the case, as COVID-19 seems to evolve more slowly
than most other viruses. But that also means we have more time to develop a vaccine that works before the virus changes.
I think the general population should continue to value the lives of their neighbors over the inconveniences of wearing a mask and avoiding large crowds. Most places have already reopened to some degree, and it makes sense to do so as conditions improve. As long as people continue to practice social distancing, businesses can keep reopening and we can get back to something closer to normal. But restrictions are likely to be in place until a substantial percentage of the population has been vaccinated.