Is this community forum an app?

What you created is what’s called a Web App. The link below explains.

Turn a website into an app in Safari on iPhone - Apple Support

You're welcome. What you did was tap the share button and then add to home screen.

No.

Your description of what you did makes very little sense.

You’re welcome. I do that with the iPhone User Guide and add it to my iPhone Home Screen and use it to find answer to questions I have and how to expand my user experience.

No, this forum isn't an App, but when you copied the link to your iPhone home screen, you created what appears to be an app, but is just a shortcut to the forum link.