All flu is a virus, dumbass. WHO called the Covid virus a flu. So did the U.S. government. For all effective purposes, it's a flu.
I very much doubt either the WHO nor anyone of any intelligence in the US Government called it a flu. Influenza is a very different virus in a very different family of viruses. It has some of the same effects on the body, but looks very different under a microscope, and has evolved differently for hundreds of millions of years.
Even the same effects on the body are somewhat superficial. Covid-19 infects all the tissues of the body, which is actually quite rare. Influenza usually only infects a few tissues in one or two organs. We assume people are recovering from Covid-19, but quite possibly it continues to lurk in the body even after supposed recovery. It is possible (but unlikely) the long term death rate from Covid-19 is similar to the long term death rate from HIV, basically 100%.