iMac7,1 - Need to upgrade to macOS v10.14 or later.

Hi there -

Regrettably, you cannot run macOS Mojave on your iMac. You would need a newer Mac. The latest version of macOS that is supported on your iMac is OS X El Capitan. If you aren't already running El Capitan, you can get it here: How to download and install macOS - Apple Support.

-Jack

Your model ID indicates that you have a 20- or 24-inch mid-2007 iMac. That model is about 16 years old, and your iMac would have originally came with a version of Tiger (10.4) or Leopard (10.5).

El Capitan (10.11) is three major versions behind Mojave (10.14), and seven major versions behind Ventura (13).

It is old enough that even LibreOffice, GIMP, etc. have moved past it; though you may be able to find compatible older versions of those programs in their archives.

The current version of OS X El Capitan is version 10.11.6. If you aren't already running that version, you can upgrade using this link: How to download and install macOS - Apple Support.

-Jack

Note that Lion and above do not support the original Rosetta. If you are still running PowerPC-only apps under Tiger, Leopard, or Snow Leopard, be aware that those apps will not run under El Capitan.