Google Sheets overrides the original data. If you want to use full names later, copy the rows, paste them to another column or sheet, and run the Split text to columns function.

So there you go, a solution to split full names into first and last names, no matter how long the names. Time to split some names yourself!

Learn how to use the Text to Columns options to split comma seperated text in Microsoft Excel. You can do the same in Google Sheets as well.