I heard an interview with a public health type on NPR the other day. He said that the flu is far more dangerous than corona virus because the flu is far more common. We forget how dangerous flu is because it's relatively common and we are used to it, but people die from it every year.
The best self-diagnosis I ever heard about "do I have the flu?" is:
If you think you have the flu, you have a cold.
If you think you're going to die, you have the flu.
If dying sounds like a good idea, go to the hospital.
I had the flu once as an adult (Feb 2014) and it was the most miserable week I can remember. I couldn't get out of bed for a week. Getting up to go to the bathroom was exhausting, and it was all I could do to collapse back into bed afterwards.
Get a flu shot. The worst it can do is protect you against the wrong strains.