I did not know that. The computer still works perfectly. Is Apple telling me to buy a new computer or is there some way to update it to a newer version(s)?
Apple isn't "telling you" anything. Your computer will continue to work indefinitely with the OS version and the applications that you currently have on it. You can continue to use it until either repairs become more costly than you want to invest in a ten year old-plus computer, or until you decide that there are more modern applications available that you would like access to which would require a new computer.
Extremely few users keep on using the same personal computer for much longer than ten years. I usually recommend that business users plan to buy a new computer after their current computer is five years od, and that home users buy a new computer after their current computer is seven years old, to avoid technology drift. (That is, you don't want to be left so far behind that you find that your old data file's formats are too old to be able to find translators for, thus orphaning your data.)
Of course, there are users who go well beyond those recommendations. Users with internal SSD's, rather than rotating disk hard drives, sometimes have computers that can seemingly go for decades without needing repairs, assuming that those drives don't become full. However, doing so runs the risk of your SSD suddenly dying with no warning, and a dead SSD can be expensive to recover if one doesn't have a backup.
