We still don't have any firm rules regarding the use of exclamation marks. They also started showing up in the 1600's. Authors can, and do, insert them wherever they wish. However, there are guidelines. Use an exclamation mark to show that the sentence is truly emotional, or use one when the verb proceeds the noun.
Commas are old, too, and have many rules for usage.
Beginner writers can use them to indicate a short break in the sentence. Read your work out loud and add them where you would normally pause. Our ABC's came into being about 1470. After the invention of printing presses, capital letters come to be called upper case and small letters, lower case. When the old-timers set type, they placed the case with the capital letters above the case with the small letters, thus the name upper case.