Germany is the country of insurances.
You will find in Germany many insurance services for many sort of things.
Insurance for your bike, insurance if you hit someone with your bike, insurance for your dog and so on.
There are public and private Insurances.
The one that I bought for Visa purposes was an international one that I found on Google.
It helped to get the visa, but I think it is changing now.
Eventually, when I was at the Rathaus they asked me to get a German Health Insurance.
So I went directly to get AOK Insurance, because I already knew it since Pforzheim.
When selecting an Insurance I recommend the following.
Besides the price, see if the health insurance will cover the payments that you have to do when you visit the doctor.
With AOK, I didn’t have to worry about paying the doctor visits that I did.
There are other insurances like Techniker Krankenkasse or Mawista. I know that the first one is also good, and Mawista is cheaper, but I think you have to pay first and then they do the rembuirsment.
But if you want to go for the easy solution, AOK is fine.